From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Samuel Attard <samuel.r.attard@gmail.com>
Date: Thu, 20 Sep 2018 17:48:49 -0700
Subject: mas: avoid private macOS API usage

* Use the stub killring file when building blink
* Remove usage of the following private APIs
  * abort_report_np
  * pthread_fchdir_np
  * pthread_chdir_np
  * SetApplicationIsDaemon
  * _LSSetApplicationLaunchServicesServerConnectionStatus
  * AreDeviceAndUserJoinedToDomain
  * _CFIsObjC
  * AudioDeviceDuck
  * NSNextStepFrame
  * NSThemeFrame
  * NSTextInputReplacementRangeAttributeName
* NSAccessibilityRemoteUIElement is unnecessary for Electron's use-case. We use it
for progressive web apps (where the AXTree is in the browser process, but macOS
needs to think it's coming from the PWA process). I think it can just be chopped
out -- if there are any side-effects, we should be able to work around them.
* CAContext removal
  * For apps that spend a lot of time watching video (especially fullscreen video),
    the power/battery usage will likely increase 1.5x to 2x. For something that is,
    e.g, scrolling, it'll be smaller, more like 1.15x or 1.25x.

    In terms of performance, the impact will likely be fairly small -- any app that
    could hit 60fps before will likely still be able to hit 60fps. There may even be
    cases where performance improves when disabling remote CoreAnimation (remote
    CoreAnimation is really only about battery usage).
* CTFontDescriptorIsSystemUIFont is a private API, we're using an
_interesting_ technique in the MAS build to determine if the font is a
system font by checking if it's kCTFontPriorityAttribute is set to
system priority.

diff --git a/base/BUILD.gn b/base/BUILD.gn
index 9c05322b1599410c1b04334315be29cfbb8fc6d7..18cc427e0d3c0b39d78668784c8304ab0bf87658 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1052,6 +1052,7 @@ component("base") {
     "//build/config/compiler:prevent_unsafe_narrowing",
     "//build/config/compiler:wexit_time_destructors",
     "//build/config/compiler:wglobal_constructors",
+    "//electron/build/config:mas_build",
   ]
 
   deps = [
diff --git a/base/enterprise_util_mac.mm b/base/enterprise_util_mac.mm
index 4bf9a3c27e05c6635b2beb8e880b5b43dbed61b5..57d4756c0d87b9313e8566b3083c0132966fcd78 100644
--- a/base/enterprise_util_mac.mm
+++ b/base/enterprise_util_mac.mm
@@ -116,6 +116,14 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
     DeviceUserDomainJoinState state{.device_joined = false,
                                     .user_joined = false};
 
+#if IS_MAS_BUILD()
+    return state;
+  }();
+
+  return state;
+}
+#else
+
     @autoreleasepool {
       ODSession* session = [ODSession defaultSession];
       if (session == nil) {
@@ -219,5 +227,6 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
 
   return state;
 }
+#endif
 
 }  // namespace base
diff --git a/base/process/launch_mac.cc b/base/process/launch_mac.cc
index 99d801d0fe89804bd87851c87f1ce76acff9f894..327c93478f491d098464f40dac7b936492f6e6fa 100644
--- a/base/process/launch_mac.cc
+++ b/base/process/launch_mac.cc
@@ -21,13 +21,18 @@
 #include "base/threading/scoped_blocking_call.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/base_tracing.h"
+#if IS_MAS_BUILD()
+#include <sys/syscall.h>
+#endif
 
 extern "C" {
 // Changes the current thread's directory to a path or directory file
 // descriptor.
+#if !IS_MAS_BUILD()
 int pthread_chdir_np(const char* dir);
 
 int pthread_fchdir_np(int fd);
+#endif
 
 int responsibility_spawnattrs_setdisclaim(posix_spawnattr_t attrs,
                                           int disclaim);
@@ -99,13 +104,27 @@ class PosixSpawnFileActions {
 
 #if !BUILDFLAG(IS_MAC)
 int ChangeCurrentThreadDirectory(const char* path) {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_chdir, path);
+  #pragma clang diagnostic pop
+#else
   return pthread_chdir_np(path);
+#endif
 }
 
 // The recommended way to unset a per-thread cwd is to set a new value to an
 // invalid file descriptor, per libpthread-218.1.3/private/private.h.
 int ResetCurrentThreadDirectory() {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_fchdir, -1);
+  #pragma clang diagnostic pop
+#else
   return pthread_fchdir_np(-1);
+#endif
 }
 #endif
 
@@ -226,7 +245,7 @@ Process LaunchProcess(const std::vector<std::string>& argv,
     file_actions.Inherit(STDERR_FILENO);
   }
 
-#if BUILDFLAG(IS_MAC)
+#if 0
   if (options.disclaim_responsibility) {
     DPSXCHECK(responsibility_spawnattrs_setdisclaim(attr.get(), 1));
   }
diff --git a/base/process/process_info_mac.cc b/base/process/process_info_mac.cc
index 94a028be3c315edc0056408ab9ab41b6b001a1c1..0d830234edb5621f57e39f4a951d357a23f677c1 100644
--- a/base/process/process_info_mac.cc
+++ b/base/process/process_info_mac.cc
@@ -8,15 +8,21 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+#if !IS_MAS_BUILD()
 extern "C" {
 pid_t responsibility_get_pid_responsible_for_pid(pid_t);
 }
+#endif
 
 namespace base {
 
 bool IsProcessSelfResponsible() {
+#if !IS_MAS_BUILD()
   const pid_t pid = getpid();
   return responsibility_get_pid_responsible_for_pid(pid) == pid;
+#else
+  return true;
+#endif
 }
 
 }  // namespace base
diff --git a/components/os_crypt/sync/BUILD.gn b/components/os_crypt/sync/BUILD.gn
index 4fe7a0bfaa5b3398372f55c6454e738f140efe6b..b1c70281c45aaca4ae483f1f28e9d21929d17815 100644
--- a/components/os_crypt/sync/BUILD.gn
+++ b/components/os_crypt/sync/BUILD.gn
@@ -46,6 +46,7 @@ component("os_crypt") {
       "os_crypt_mac.mm",
     ]
     deps += [ "//crypto:mock_apple_keychain" ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_win) {
diff --git a/components/remote_cocoa/app_shim/BUILD.gn b/components/remote_cocoa/app_shim/BUILD.gn
index 459f14da45419a2a0340199d9cf311e3bba437e6..3b7908c559ddd3d6101801f8de256aa80a9411a2 100644
--- a/components/remote_cocoa/app_shim/BUILD.gn
+++ b/components/remote_cocoa/app_shim/BUILD.gn
@@ -16,6 +16,7 @@ component("app_shim") {
   assert(is_mac)
 
   configs += [ ":app_shim_warnings" ]
+  configs += ["//electron/build/config:mas_build"]
   sources = [
     "NSToolbar+Private.h",
     "NSToolbar+Private.mm",
diff --git a/components/remote_cocoa/app_shim/application_bridge.mm b/components/remote_cocoa/app_shim/application_bridge.mm
index c8682418893584aaf61eb6db859b30c99b064698..5d1550030b519f3599dcb855007b25180f0606e9 100644
--- a/components/remote_cocoa/app_shim/application_bridge.mm
+++ b/components/remote_cocoa/app_shim/application_bridge.mm
@@ -50,6 +50,7 @@
 
   // NativeWidgetNSWindowHostHelper:
   id GetNativeViewAccessible() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -60,6 +61,9 @@ id GetNativeViewAccessible() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
   void DispatchKeyEvent(ui::KeyEvent* event) override {
     bool event_handled = false;
@@ -98,7 +102,9 @@ void GetWordAt(const gfx::Point& location_in_content,
   mojo::AssociatedRemote<mojom::TextInputHost> text_input_host_remote_;
 
   std::unique_ptr<NativeWidgetNSWindowBridge> bridge_;
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
 };
 
 }  // namespace
diff --git a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
index 53553a707a646012c50b0bd2d0ffd8d4dbd67e11..e9df78b2cf8ca8cb4cb8321769e9a56b96d368b6 100644
--- a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
+++ b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
@@ -9,6 +9,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
 
+#if !IS_MAS_BUILD()
 @interface NSWindow (PrivateBrowserNativeWidgetAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -65,10 +66,13 @@ - (BOOL)_shouldCenterTrafficLights {
 
 @end
 
+#endif  // MAS_BUILD
+
 @implementation BrowserNativeWidgetWindow
 
 // NSWindow (PrivateAPI) overrides.
 
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   // - NSThemeFrame and its subclasses will be nil if it's missing at runtime.
   if ([BrowserWindowFrame class])
@@ -115,6 +119,8 @@ - (BOOL)_usesCustomDrawing {
   return NO;
 }
 
+#endif  // MAS_BUILD
+
 // Handle "Move focus to the window toolbar" configured in System Preferences ->
 // Keyboard -> Shortcuts -> Keyboard. Usually Ctrl+F5. The argument (|unknown|)
 // tends to just be nil.
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
index 3a815ebf505bd95fa7f6b61ba433d98fbfe20225..dbbebbdc1735bc14224dfcde0b7fe3a6fd9f9e40 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
@@ -4,6 +4,8 @@
 
 #import "components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.h"
 
+#if !IS_MAS_BUILD()
+
 @interface NSWindow (PrivateAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -18,8 +20,12 @@ - (CGFloat)_titlebarHeight {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacFramelessNSWindow
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   if ([NativeWidgetMacFramelessNSWindowFrame class]) {
     return [NativeWidgetMacFramelessNSWindowFrame class];
@@ -27,4 +33,6 @@ + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif  // MAS_BUILD
+
 @end
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
index 945b01f2132547fa0f6a97ee4895994c500d1410..c01b2fdecf9b54fa01e5be9f45eaa234fc42d06b 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
@@ -17,6 +17,7 @@ class NativeWidgetNSWindowBridge;
 
 @protocol WindowTouchBarDelegate;
 
+#if !IS_MAS_BUILD()
 // Weak lets Chrome launch even if a future macOS doesn't have the below classes
 WEAK_IMPORT_ATTRIBUTE
 @interface NSNextStepFrame : NSView
@@ -33,6 +34,7 @@ REMOTE_COCOA_APP_SHIM_EXPORT
 REMOTE_COCOA_APP_SHIM_EXPORT
 @interface NativeWidgetMacNSWindowTitledFrame : NSThemeFrame
 @end
+#endif
 
 // The NSWindow used by BridgedNativeWidget. Provides hooks into AppKit that
 // can only be accomplished by overriding methods.
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
index 6ebc4754ef986f5ae966ff7a3217ab77df78edf9..91147b8a42f731c645c318776933b4c139ca606d 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
@@ -104,7 +104,9 @@ void OrderChildWindow(NSWindow* child_window,
 }  // namespace
 
 @interface NSWindow (Private)
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle;
+#endif
 - (BOOL)hasKeyAppearance;
 - (long long)_resizeDirectionForMouseLocation:(CGPoint)location;
 - (BOOL)_isConsideredOpenForPersistentState;
@@ -143,6 +145,8 @@ - (void)cr_mouseDownOnFrameView:(NSEvent*)event {
 }
 @end
 
+#if !IS_MAS_BUILD()
+
 @implementation NativeWidgetMacNSWindowTitledFrame
 - (void)mouseDown:(NSEvent*)event {
   if (self.window.isMovable)
@@ -169,6 +173,8 @@ - (BOOL)usesCustomDrawing {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacNSWindow {
  @private
   CommandDispatcher* __strong _commandDispatcher;
@@ -357,6 +363,8 @@ - (NSAccessibilityRole)accessibilityRole {
 
 // NSWindow overrides.
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   if (windowStyle & NSWindowStyleMaskTitled) {
     if (Class customFrame = [NativeWidgetMacNSWindowTitledFrame class])
@@ -368,6 +376,8 @@ + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif
+
 - (BOOL)_isTitleHidden {
   bool shouldShowWindowTitle = YES;
   if (_bridge)
diff --git a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
index 7fbc649a45bea2181523a1875f0112021f0b9251..e15f59c3dedf587df6664cef1913a8e789497bbd 100644
--- a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
+++ b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
@@ -627,10 +627,12 @@ NSUInteger CountBridgedWindows(NSArray* child_windows) {
   // this should be treated as an error and caught early.
   CHECK(bridged_view_);
 
+#if !IS_MAS_BUILD()
   // Send the accessibility tokens for the NSView now that it exists.
   host_->SetRemoteAccessibilityTokens(
       ui::RemoteAccessibility::GetTokenForLocalElement(window_),
       ui::RemoteAccessibility::GetTokenForLocalElement(bridged_view_));
+#endif
 
   // Beware: This view was briefly removed (in favor of a bare CALayer) in
   // https://crrev.com/c/1236675. The ordering of unassociated layers relative
diff --git a/components/viz/service/BUILD.gn b/components/viz/service/BUILD.gn
index f28503c3bd02b51da148624b3545c7feeccad511..aeb4e82629b7d4828a6717708112f28eb9f35079 100644
--- a/components/viz/service/BUILD.gn
+++ b/components/viz/service/BUILD.gn
@@ -362,6 +362,7 @@ viz_component("service") {
         "frame_sinks/external_begin_frame_source_mac.h",
       ]
     }
+    configs = ["//electron/build/config:mas_build"]
   }
 
   if (is_android || use_ozone) {
@@ -633,6 +634,7 @@ viz_source_set("unit_tests") {
       "display_embedder/software_output_device_mac_unittest.mm",
     ]
     frameworks = [ "IOSurface.framework" ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_win) {
diff --git a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
index dbf334caa3a6d10017b69ad76802e389a011436b..0cdb0def975e457651771b43fd5432610481c7d0 100644
--- a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
+++ b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
@@ -63,7 +63,9 @@ explicit RenderWidgetHostNSViewBridgeOwner(
       const RenderWidgetHostNSViewBridgeOwner&) = delete;
 
  private:
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
   void OnMojoDisconnect() { delete this; }
 
   std::unique_ptr<blink::WebCoalescedInputEvent> TranslateEvent(
@@ -75,6 +77,7 @@ explicit RenderWidgetHostNSViewBridgeOwner(
   }
 
   id GetAccessibilityElement() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -85,6 +88,9 @@ id GetAccessibilityElement() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
 
   // RenderWidgetHostNSViewHostHelper implementation.
@@ -103,8 +109,10 @@ id GetFocusedBrowserAccessibilityElement() override {
     return [bridgedContentView accessibilityFocusedUIElement];
   }
   void SetAccessibilityWindow(NSWindow* window) override {
+#if !IS_MAS_BUILD()
     host_->SetRemoteAccessibilityWindowToken(
         ui::RemoteAccessibility::GetTokenForLocalElement(window));
+#endif
   }
 
   void ForwardKeyboardEvent(const input::NativeWebKeyboardEvent& key_event,
diff --git a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
index ea7957d89c1c44ce7cae2f0d4548fb67b60543ca..04f78e4f395df7ad3be39ff4a373e0d72811f587 100644
--- a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
+++ b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
@@ -2063,15 +2063,21 @@ - (NSAccessibilityRole)accessibilityRole {
 // Since this implementation doesn't have to wait any IPC calls, this doesn't
 // make any key-typing jank. --hbono 7/23/09
 //
+#if !IS_MAS_BUILD()
 extern "C" {
 extern NSString* NSTextInputReplacementRangeAttributeName;
 }
+#endif
 
 - (NSArray*)validAttributesForMarkedText {
   // This code is just copied from WebKit except renaming variables.
   static NSArray* const kAttributes = @[
     NSUnderlineStyleAttributeName, NSUnderlineColorAttributeName,
+#if !IS_MAS_BUILD()
     NSMarkedClauseSegmentAttributeName, NSTextInputReplacementRangeAttributeName
+#else
+    NSMarkedClauseSegmentAttributeName
+#endif
   ];
   return kAttributes;
 }
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 6d5fd4133598c17a2dfcf1a4bd2732435353ed1f..24b1ea6fc5fef18b199518ae730713baaa8c0530 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -54,6 +54,7 @@ source_set("browser") {
     "//content:content_implementation",
     "//v8:external_startup_data",
   ]
+  configs += ["//electron/build/config:mas_build"]
   defines = []
   libs = []
   frameworks = []
diff --git a/content/browser/accessibility/browser_accessibility_manager_mac.mm b/content/browser/accessibility/browser_accessibility_manager_mac.mm
index b1dd00ab48e22e1e248728e0400b00e92553e8fd..253670f014c4fc13ad99d674e8dcbf145c17fcc7 100644
--- a/content/browser/accessibility/browser_accessibility_manager_mac.mm
+++ b/content/browser/accessibility/browser_accessibility_manager_mac.mm
@@ -20,7 +20,9 @@
 #include "ui/accessibility/ax_role_properties.h"
 #include "ui/accessibility/platform/ax_platform_tree_manager_delegate.h"
 #include "ui/accessibility/platform/ax_private_webkit_constants_mac.h"
+#if !IS_MAS_BUILD()
 #include "ui/base/cocoa/remote_accessibility_api.h"
+#endif
 
 namespace {
 
@@ -224,6 +226,7 @@ void PostAnnouncementNotification(NSString* announcement,
         return;
       }
 
+#if !IS_MAS_BUILD()
       BrowserAccessibilityManager* root_manager = GetManagerForRootFrame();
       if (root_manager) {
         BrowserAccessibilityManagerMac* root_manager_mac =
@@ -246,6 +249,7 @@ void PostAnnouncementNotification(NSString* announcement,
           return;
         }
       }
+#endif
 
       // Use native VoiceOver support for live regions.
       BrowserAccessibilityCocoa* retained_node = native_node;
@@ -647,6 +651,7 @@ void PostAnnouncementNotification(NSString* announcement,
     return window == [NSApp accessibilityFocusedWindow];
   }
 
+#if !IS_MAS_BUILD()
   // TODO(accessibility): We need a solution to the problem described below.
   // If the window is NSAccessibilityRemoteUIElement, there are some challenges:
   // 1. NSApp is the browser which spawned the PWA, and what it considers the
@@ -675,6 +680,7 @@ void PostAnnouncementNotification(NSString* announcement,
   if ([window isKindOfClass:[NSAccessibilityRemoteUIElement class]]) {
     return true;
   }
+#endif
 
   return false;
 }
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index fe37e5d17d217ad2a7861ac9dba2e61de5a063aa..ab8c04e648f320412de16ce31c134b28c11eb01e 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -49,7 +49,9 @@ class ScopedPasswordInputEnabler;
 
 @protocol RenderWidgetHostViewMacDelegate;
 
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class RenderWidgetHostViewCocoa;
 @class CursorAccessibilityScaleFactorObserver;
 
@@ -682,9 +684,11 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // EnsureSurfaceSynchronizedForWebTest().
   uint32_t latest_capture_sequence_number_ = 0u;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow that this is
   // displayed to the user in.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // content::BrowserAccessibilityCocoa accessibility tree when the NSView for
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index e9a73bafeb1ef85ef6ebbc870b66fbde2076b306..679c9e92ef3f8e984e8cc4d6b99afbbf33383e8b 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -272,8 +272,10 @@
 void RenderWidgetHostViewMac::MigrateNSViewBridge(
     remote_cocoa::mojom::Application* remote_cocoa_application,
     uint64_t parent_ns_view_id) {
+#if !IS_MAS_BUILD()
   // Destroy the previous remote accessibility element.
   remote_window_accessible_ = nil;
+#endif
 
   // Reset `ns_view_` before resetting `remote_ns_view_` to avoid dangling
   // pointers. `ns_view_` gets reinitialized later in this method.
@@ -1654,8 +1656,10 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 
 gfx::NativeViewAccessible
 RenderWidgetHostViewMac::AccessibilityGetNativeViewAccessibleForWindow() {
+#if !IS_MAS_BUILD()
   if (remote_window_accessible_)
     return remote_window_accessible_;
+#endif
   return [GetInProcessNSView() window];
 }
 
@@ -1704,9 +1708,11 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 }
 
 void RenderWidgetHostViewMac::SetAccessibilityWindow(NSWindow* window) {
+#if !IS_MAS_BUILD()
   // When running in-process, just use the NSView's NSWindow as its own
   // accessibility element.
   remote_window_accessible_ = nil;
+#endif
 }
 
 bool RenderWidgetHostViewMac::SyncIsWidgetForMainFrame(
@@ -2230,20 +2236,26 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 void RenderWidgetHostViewMac::GetRenderWidgetAccessibilityToken(
     GetRenderWidgetAccessibilityTokenCallback callback) {
   base::ProcessId pid = getpid();
+#if !IS_MAS_BUILD()
   id element_id = GetNativeViewAccessible();
   std::vector<uint8_t> token =
       ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
   std::move(callback).Run(pid, token);
+#else
+  std::move(callback).Run(pid, std::vector<uint8_t>());
+#endif
 }
 
 void RenderWidgetHostViewMac::SetRemoteAccessibilityWindowToken(
     const std::vector<uint8_t>& window_token) {
+#if !IS_MAS_BUILD()
   if (window_token.empty()) {
     remote_window_accessible_ = nil;
   } else {
     remote_window_accessible_ =
         ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   }
+#endif
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/content/common/BUILD.gn b/content/common/BUILD.gn
index 4d169795cd87c26d2264f4b89334f50c532bc4e7..365154bac05faec52591cc6b4138dcf0bbcadcbb 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -249,6 +249,7 @@ source_set("common") {
     "//content:content_implementation",
     "//build/config:precompiled_headers",
   ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":mojo_bindings",
diff --git a/content/renderer/BUILD.gn b/content/renderer/BUILD.gn
index 4acb73f39de91b9dfd9b1e6d25c911983c91dc93..22513b5aa30d0fa549d06d5d58312b0a2aa07b27 100644
--- a/content/renderer/BUILD.gn
+++ b/content/renderer/BUILD.gn
@@ -226,6 +226,7 @@ target(link_target_type, "renderer") {
   }
 
   configs += [ "//content:content_implementation" ]
+  configs += ["//electron/build/config:mas_build"]
   defines = []
 
   public_deps = [
diff --git a/content/renderer/renderer_main_platform_delegate_mac.mm b/content/renderer/renderer_main_platform_delegate_mac.mm
index d4db3b179725cb96bcbd0f73db7d52ef8b7522db..6afbf1defb0591d9fe59a81e6c74746d3e15f081 100644
--- a/content/renderer/renderer_main_platform_delegate_mac.mm
+++ b/content/renderer/renderer_main_platform_delegate_mac.mm
@@ -10,9 +10,11 @@
 #include "sandbox/mac/seatbelt.h"
 #include "sandbox/mac/system_services.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 CGError CGSSetDenyWindowServerConnections(bool);
 }
+#endif
 
 namespace content {
 
@@ -22,6 +24,7 @@
 // verifies there are no existing open connections), and then indicates that
 // Chrome should continue execution without access to launchservicesd.
 void DisableSystemServices() {
+#if !IS_MAS_BUILD()
   // Tell the WindowServer that we don't want to make any future connections.
   // This will return Success as long as there are no open connections, which
   // is what we want.
@@ -30,6 +33,7 @@ void DisableSystemServices() {
 
   sandbox::DisableLaunchServices();
   sandbox::DisableCoreServicesCheckFix();
+#endif
 }
 
 }  // namespace
diff --git a/content/renderer/theme_helper_mac.mm b/content/renderer/theme_helper_mac.mm
index a119b4439bfb9218c7aaf09dca8e78527da7f20d..faa813b003940280c6eeb87e70173019bdd5280c 100644
--- a/content/renderer/theme_helper_mac.mm
+++ b/content/renderer/theme_helper_mac.mm
@@ -8,10 +8,11 @@
 
 #include "base/strings/sys_string_conversions.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CGFontRenderingGetFontSmoothingDisabled(void);
 }
-
+#endif
 namespace content {
 
 void SystemColorsDidChange(int aqua_color_variant) {
@@ -24,8 +25,18 @@ void SystemColorsDidChange(int aqua_color_variant) {
 }
 
 bool IsSubpixelAntialiasingAvailable() {
+#if !IS_MAS_BUILD()
   // See https://trac.webkit.org/changeset/239306/webkit for more info.
   return !CGFontRenderingGetFontSmoothingDisabled();
+#else
+  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
+  NSString *default_key = @"CGFontRenderingGetFontSmoothingDisabled";
+  // Check that key exists since boolForKey defaults to NO when the
+  // key is missing and this key in fact defaults to YES;
+  if ([defaults objectForKey:default_key] == nil)
+    return false;
+  return ![defaults boolForKey:default_key];
+#endif
 }
 
 }  // namespace content
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 02b51f9dae40ed3976cf43a7d5cf837ea639d7c9..ca71960c438930e59e372ff3ad7837cb6d9e34d4 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -504,6 +504,7 @@ static_library("test_support") {
   configs += [
     "//build/config:precompiled_headers",
     "//v8:external_startup_data",
+    "//electron/build/config:mas_build",
   ]
 
   public_deps = [
@@ -1103,6 +1104,7 @@ static_library("browsertest_support") {
   }
 
   configs += [ "//v8:external_startup_data" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 mojom("content_test_mojo_bindings") {
@@ -1718,6 +1720,7 @@ test("content_browsertests") {
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 
   configs += [ "//build/config:precompiled_headers" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":test_interfaces",
@@ -2971,6 +2974,7 @@ test("content_unittests") {
   }
 
   configs += [ "//build/config:precompiled_headers" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [ "//content:content_resources" ]
 
diff --git a/content/web_test/BUILD.gn b/content/web_test/BUILD.gn
index c28458b5ddc8ef74e82125a983344b1daf65dda6..48e6d48962a2228d26444dbdbcfa1637e67a8c56 100644
--- a/content/web_test/BUILD.gn
+++ b/content/web_test/BUILD.gn
@@ -151,6 +151,8 @@ static_library("web_test_browser") {
     "browser/web_test_tts_platform.h",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   if (is_mac) {
     sources += [ "browser/web_test_shell_platform_delegate_mac.mm" ]
   } else if (toolkit_views && !is_castos) {
diff --git a/device/bluetooth/BUILD.gn b/device/bluetooth/BUILD.gn
index 05cce11f233e04e22bf9166ee107661900686bea..70268a1ff7c59a03903072fafe8b62acc3454287 100644
--- a/device/bluetooth/BUILD.gn
+++ b/device/bluetooth/BUILD.gn
@@ -248,6 +248,7 @@ component("bluetooth") {
       "IOKit.framework",
       "Foundation.framework",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_mac) {
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index cda4f747099492c306db22c6dba98249e443cd74..f63dbbe7149010efa06c9cbb215399eb9e882cb9 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -39,6 +39,7 @@
 #include "device/bluetooth/bluetooth_socket_mac.h"
 #include "device/bluetooth/public/cpp/bluetooth_address.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 // Undocumented IOBluetooth Preference API [1]. Used by `blueutil` [2] and
 // `Karabiner` [3] to programmatically control the Bluetooth state. Calling the
@@ -52,6 +53,7 @@
 // [4] https://support.apple.com/kb/PH25091
 void IOBluetoothPreferenceSetControllerPowerState(int state);
 }
+#endif
 
 namespace {
 
@@ -103,8 +105,10 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
     : controller_state_function_(
           base::BindRepeating(&BluetoothAdapterMac::GetHostControllerState,
                               base::Unretained(this))),
+#if !IS_MAS_BUILD()
       power_state_function_(
           base::BindRepeating(IOBluetoothPreferenceSetControllerPowerState)),
+#endif
       device_paired_status_callback_(
           base::BindRepeating(&IsDeviceSystemPaired)) {
 }
@@ -252,8 +256,12 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
 }
 
 bool BluetoothAdapterMac::SetPoweredImpl(bool powered) {
+#if !IS_MAS_BUILD()
   power_state_function_.Run(base::strict_cast<int>(powered));
   return true;
+#else
+  return false;
+#endif
 }
 
 base::WeakPtr<BluetoothLowEnergyAdapterApple>
diff --git a/gpu/ipc/service/BUILD.gn b/gpu/ipc/service/BUILD.gn
index a4f541e3f4095a0f537137ae371555adc80c0023..f93f0b5bf8c47efbc67039d50e3bcd29e099459c 100644
--- a/gpu/ipc/service/BUILD.gn
+++ b/gpu/ipc/service/BUILD.gn
@@ -135,6 +135,7 @@ component("service") {
       "QuartzCore.framework",
     ]
     defines += [ "GL_SILENCE_DEPRECATION" ]
+    configs += ["//electron/build/config:mas_build"]
   }
   if (is_ios) {
     sources += [ "image_transport_surface_ios.mm" ]
diff --git a/gpu/ipc/service/image_transport_surface_overlay_mac.h b/gpu/ipc/service/image_transport_surface_overlay_mac.h
index d75db1f8fbdf12cf07ba19e3f2c68136ef33f021..dc0238d5a78b434c722b84adf3dbbcebaa19e847 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.h
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.h
@@ -23,7 +23,9 @@
 #include "ui/display/types/display_constants.h"
 #endif
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
diff --git a/media/audio/BUILD.gn b/media/audio/BUILD.gn
index 90e093cd2d499ba0f37f3246bab288c758b51e19..6027134a4de53e6fe39fdbfdb67885e0b5f56e40 100644
--- a/media/audio/BUILD.gn
+++ b/media/audio/BUILD.gn
@@ -199,6 +199,7 @@ source_set("audio") {
       "CoreMedia.framework",
     ]
     weak_frameworks = [ "ScreenCaptureKit.framework" ]  # macOS 13.0
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_ios) {
diff --git a/media/audio/apple/audio_low_latency_input.cc b/media/audio/apple/audio_low_latency_input.cc
index 808f4e1c7beb03cc5377465882940eea94ad61a7..d001436c3a5a8a0fc25995519772478f04ddb35f 100644
--- a/media/audio/apple/audio_low_latency_input.cc
+++ b/media/audio/apple/audio_low_latency_input.cc
@@ -34,19 +34,23 @@
 
 namespace {
 extern "C" {
+#if !IS_MAS_BUILD()
 // See:
 // https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/PAL/pal/spi/cf/CoreAudioSPI.h?rev=228264
 OSStatus AudioDeviceDuck(AudioDeviceID inDevice,
                          Float32 inDuckedLevel,
                          const AudioTimeStamp* __nullable inStartTime,
                          Float32 inRampDuration) __attribute__((weak_import));
+#endif
 }
 
 void UndoDucking(AudioDeviceID output_device_id) {
+#if !IS_MAS_BUILD()
   if (AudioDeviceDuck != nullptr) {
     // Ramp the volume back up over half a second.
     AudioDeviceDuck(output_device_id, 1.0, nullptr, 0.5);
   }
+#endif
 }
 }  // namespace
 #endif
diff --git a/media/audio/mac/audio_manager_mac.cc b/media/audio/mac/audio_manager_mac.cc
index a5070091785d80a47d1d9d9977803cd1de8b2054..b280a0d58fc03257aa1763cd15791db4ddede7c1 100644
--- a/media/audio/mac/audio_manager_mac.cc
+++ b/media/audio/mac/audio_manager_mac.cc
@@ -971,7 +971,7 @@ AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
 
 void AudioManagerMac::InitializeOnAudioThread() {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  InitializeCoreAudioDispatchOverride();
+  // InitializeCoreAudioDispatchOverride();
   power_observer_ = std::make_unique<AudioPowerObserver>();
 }
 
diff --git a/net/dns/BUILD.gn b/net/dns/BUILD.gn
index 63414d8db326c0fdd44ed59f99400d5c16cfc93c..d80a104451c66017750d04c776355cfa4691d2a3 100644
--- a/net/dns/BUILD.gn
+++ b/net/dns/BUILD.gn
@@ -187,6 +187,8 @@ source_set("dns") {
     ":host_resolver_manager",
     ":mdns_client",
   ]
+
+  configs += ["//electron/build/config:mas_build"]
 }
 
 # The standard API of net/dns.
diff --git a/net/dns/dns_config_service_posix.cc b/net/dns/dns_config_service_posix.cc
index 70d5665ad7b9ef62370497636af919ede2508ad4..3f6816de14f4bd19422a2b04830649d1d12e9179 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -135,8 +135,8 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
 
   bool Watch() override {
     CheckOnCorrectSequence();
-
     bool success = true;
+#if !IS_MAS_BUILD()
     if (!config_watcher_.Watch(base::BindRepeating(&Watcher::OnConfigChanged,
                                                    base::Unretained(this)))) {
       LOG(ERROR) << "DNS config watch failed to start.";
@@ -153,6 +153,7 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
       success = false;
     }
 #endif  // !BUILDFLAG(IS_IOS)
+#endif
     return success;
   }
 
diff --git a/sandbox/mac/BUILD.gn b/sandbox/mac/BUILD.gn
index 299a028f23314f479d2da8f914a5bdf34698d854..672dcb04dd3cf4e3cc71403f727a1dde91ad4402 100644
--- a/sandbox/mac/BUILD.gn
+++ b/sandbox/mac/BUILD.gn
@@ -39,6 +39,7 @@ component("seatbelt") {
   ]
   public_deps = [ "//third_party/protobuf:protobuf_lite" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 component("seatbelt_extension") {
@@ -52,6 +53,7 @@ component("seatbelt_extension") {
   libs = [ "sandbox" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 component("system_services") {
@@ -66,6 +68,7 @@ component("system_services") {
   deps = [ ":seatbelt_export" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 source_set("sandbox_unittests") {
diff --git a/sandbox/mac/sandbox_compiler.cc b/sandbox/mac/sandbox_compiler.cc
index f35d9ef2a2df3db8ecbf1d7b909c7b1cf33f3cd9..a710b8b4f851666fd65bb37f69ec2fa70259697b 100644
--- a/sandbox/mac/sandbox_compiler.cc
+++ b/sandbox/mac/sandbox_compiler.cc
@@ -47,6 +47,7 @@ bool SandboxCompiler::SetParameter(const std::string& key,
 }
 
 bool SandboxCompiler::CompileAndApplyProfile(std::string& error) {
+#if !IS_MAS_BUILD()
   if (mode_ == Target::kSource) {
     std::vector<const char*> params;
 
@@ -67,6 +68,9 @@ bool SandboxCompiler::CompileAndApplyProfile(std::string& error) {
     }
   }
   return false;
+#else
+  return true;
+#endif
 }
 
 bool SandboxCompiler::CompilePolicyToProto(mac::SandboxPolicy& policy,
diff --git a/sandbox/mac/sandbox_logging.cc b/sandbox/mac/sandbox_logging.cc
index 095c639b9893e885d8937e29ed7d47a7c28bc6b6..cfa5e307de8326fbc335996feaf9595d1572cd3d 100644
--- a/sandbox/mac/sandbox_logging.cc
+++ b/sandbox/mac/sandbox_logging.cc
@@ -33,9 +33,11 @@
   }
 #endif
 
+#if !IS_MAS_BUILD()
 extern "C" {
 void abort_report_np(const char*, ...);
 }
+#endif
 
 namespace sandbox::logging {
 
@@ -76,9 +78,11 @@ void SendOsLog(Level level, const char* message) {
     sandbox::crash_message::SetCrashMessage(message);
   }
 
+#if !IS_MAS_BUILD()
   if (level == Level::FATAL) {
     abort_report_np(message);
   }
+#endif
 }
 
 // |error| is strerror(errno) when a P* logging function is called. Pass
diff --git a/sandbox/mac/seatbelt.cc b/sandbox/mac/seatbelt.cc
index 15c835e118456394c0a00ac98c11241c14ca75bd..83759e5fbc252fa57ca2fa122873dfac3d61d46d 100644
--- a/sandbox/mac/seatbelt.cc
+++ b/sandbox/mac/seatbelt.cc
@@ -9,7 +9,7 @@
 
 extern "C" {
 #include <sandbox.h>
-
+#if !IS_MAS_BUILD()
 int sandbox_init_with_parameters(const char* profile,
                                  uint64_t flags,
                                  const char* const parameters[],
@@ -40,13 +40,13 @@ sandbox_profile_t* sandbox_compile_string(const char* data,
                                           char** error);
 int sandbox_apply(sandbox_profile_t*);
 void sandbox_free_profile(sandbox_profile_t*);
-
+#endif
 }  // extern "C"
 
 namespace sandbox {
 
 namespace {
-
+#if !IS_MAS_BUILD()
 bool HandleSandboxResult(int rv, char* errorbuf, std::string* error) {
   if (rv == 0) {
     if (error)
@@ -74,36 +74,48 @@ bool HandleSandboxErrno(int rv, const char* message, std::string* error) {
   }
   return false;
 }
-
+#endif
 }  // namespace
 
 // static
 Seatbelt::Parameters Seatbelt::Parameters::Create() {
   Parameters params;
+#if !IS_MAS_BUILD()
   params.params_ = ::sandbox_create_params();
+#endif
   return params;
 }
 
 Seatbelt::Parameters::Parameters() = default;
 
 Seatbelt::Parameters::Parameters(Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
 }
 
 Seatbelt::Parameters& Seatbelt::Parameters::operator=(
     Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
   return *this;
 }
 
 bool Seatbelt::Parameters::Set(const char* key, const char* value) {
+#if !IS_MAS_BUILD()
   return ::sandbox_set_param(params_, key, value) == 0;
+#else
+  return true;
+#endif
 }
 
 Seatbelt::Parameters::~Parameters() {
+#if !IS_MAS_BUILD()
   if (params_) {
     ::sandbox_free_params(params_);
   }
+#endif
 }
 
 // Initialize the static member variables.
@@ -114,6 +126,7 @@ const char* Seatbelt::kProfilePureComputation = kSBXProfilePureComputation;
 
 // static
 bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
+#if !IS_MAS_BUILD()
 // OS X deprecated these functions, but did not provide a suitable replacement,
 // so ignore the deprecation warning.
 #pragma clang diagnostic push
@@ -122,6 +135,9 @@ bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
   int rv = ::sandbox_init(profile, flags, &errorbuf);
   return HandleSandboxResult(rv, errorbuf, error);
 #pragma clang diagnostic pop
+#else
+  return true;
+#endif
 }
 
 // static
@@ -129,10 +145,14 @@ bool Seatbelt::InitWithParams(const char* profile,
                               uint64_t flags,
                               const char* const parameters[],
                               std::string* error) {
+#if !IS_MAS_BUILD()
   char* errorbuf = nullptr;
   int rv =
       ::sandbox_init_with_parameters(profile, flags, parameters, &errorbuf);
   return HandleSandboxResult(rv, errorbuf, error);
+#else
+  return true;
+#endif
 }
 
 // static
@@ -140,6 +160,7 @@ bool Seatbelt::Compile(const char* profile,
                        const Seatbelt::Parameters& params,
                        std::string& compiled_profile,
                        std::string* error) {
+#if !IS_MAS_BUILD()
   char* errorbuf = nullptr;
   sandbox_profile_t* sandbox_profile =
       ::sandbox_compile_string(profile, params.params(), &errorbuf);
@@ -149,33 +170,44 @@ bool Seatbelt::Compile(const char* profile,
   compiled_profile.assign(reinterpret_cast<const char*>(sandbox_profile->data),
                           sandbox_profile->size);
   ::sandbox_free_profile(sandbox_profile);
+#endif
   return true;
 }
 
 // static
 bool Seatbelt::ApplyCompiledProfile(const std::string& profile,
                                     std::string* error) {
+#if !IS_MAS_BUILD()
   sandbox_profile_t sbox_profile = {
       .builtin = nullptr,
       .data = reinterpret_cast<const uint8_t*>(profile.data()),
       .size = profile.size()};
   return HandleSandboxErrno(::sandbox_apply(&sbox_profile),
                             "sandbox_apply: ", error);
+#else
+  return true;
+#endif
 }
 
 // static
 void Seatbelt::FreeError(char* errorbuf) {
+#if !IS_MAS_BUILD()
 // OS X deprecated these functions, but did not provide a suitable replacement,
 // so ignore the deprecation warning.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
   return ::sandbox_free_error(errorbuf);
 #pragma clang diagnostic pop
+#endif
 }
 
 // static
 bool Seatbelt::IsSandboxed() {
+#if !IS_MAS_BUILD()
   return ::sandbox_check(getpid(), NULL, 0);
+#else
+  return true;
+#endif
 }
 
 }  // namespace sandbox
diff --git a/sandbox/mac/seatbelt_extension.cc b/sandbox/mac/seatbelt_extension.cc
index b3f017a8be25209a78ed6a1221abcdeeb7904752..506d520e41f321e02b227e07b7b41a4bbfec8d4d 100644
--- a/sandbox/mac/seatbelt_extension.cc
+++ b/sandbox/mac/seatbelt_extension.cc
@@ -11,6 +11,7 @@
 #include "base/notreached.h"
 #include "sandbox/mac/seatbelt_extension_token.h"
 
+#if !IS_MAS_BUILD()
 // libsandbox private API.
 extern "C" {
 extern const char* APP_SANDBOX_READ;
@@ -22,6 +23,7 @@ char* sandbox_extension_issue_file(const char* type,
                                    const char* path,
                                    uint32_t flags);
 }
+#endif
 
 namespace sandbox {
 
@@ -50,7 +52,11 @@ std::unique_ptr<SeatbeltExtension> SeatbeltExtension::FromToken(
 
 bool SeatbeltExtension::Consume() {
   DCHECK(!token_.empty());
+#if !IS_MAS_BUILD()
   handle_ = sandbox_extension_consume(token_.c_str());
+#else
+  handle_ = -1;
+#endif
   return handle_ > 0;
 }
 
@@ -62,7 +68,11 @@ bool SeatbeltExtension::ConsumePermanently() {
 }
 
 bool SeatbeltExtension::Revoke() {
+#if !IS_MAS_BUILD()
   int rv = sandbox_extension_release(handle_);
+#else
+  int rv = -1;
+#endif
   handle_ = 0;
   token_.clear();
   return rv == 0;
@@ -80,12 +90,14 @@ SeatbeltExtension::SeatbeltExtension(const std::string& token)
 char* SeatbeltExtension::IssueToken(SeatbeltExtension::Type type,
                                     const std::string& resource) {
   switch (type) {
+#if !IS_MAS_BUILD()
     case FILE_READ:
       return sandbox_extension_issue_file(APP_SANDBOX_READ, resource.c_str(),
                                           0);
     case FILE_READ_WRITE:
       return sandbox_extension_issue_file(APP_SANDBOX_READ_WRITE,
                                           resource.c_str(), 0);
+#endif
     default:
       NOTREACHED_IN_MIGRATION();
       return nullptr;
diff --git a/sandbox/mac/system_services.cc b/sandbox/mac/system_services.cc
index eb81a70e4d5d5cd3e6ae9b45f8cd1c795ea76c51..dc30306f2c5d20503399fc3a8860773aa0044352 100644
--- a/sandbox/mac/system_services.cc
+++ b/sandbox/mac/system_services.cc
@@ -9,6 +9,7 @@
 
 #include "base/apple/osstatus_logging.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 OSStatus SetApplicationIsDaemon(Boolean isDaemon);
 void _LSSetApplicationLaunchServicesServerConnectionStatus(
@@ -19,10 +20,12 @@ void _LSSetApplicationLaunchServicesServerConnectionStatus(
 // https://github.com/WebKit/WebKit/blob/24aaedc770d192d03a07ba4a71727274aaa8fc07/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm#L840
 void _CSCheckFixDisable();
 }  // extern "C"
+#endif
 
 namespace sandbox {
 
 void DisableLaunchServices() {
+  #if !IS_MAS_BUILD()
   // Allow the process to continue without a LaunchServices ASN. The
   // INIT_Process function in HIServices will abort if it cannot connect to
   // launchservicesd to get an ASN. By setting this flag, HIServices skips
@@ -36,10 +39,13 @@ void DisableLaunchServices() {
       0, ^bool(CFDictionaryRef options) {
         return false;
       });
+  #endif
 }
 
 void DisableCoreServicesCheckFix() {
+#if !IS_MAS_BUILD()
   _CSCheckFixDisable();
+#endif
 }
 
 }  // namespace sandbox
diff --git a/third_party/blink/renderer/core/BUILD.gn b/third_party/blink/renderer/core/BUILD.gn
index 2a9d420eabfee17a39604e525af6f0fa95fafc04..0883cfc964881922f3f5b04426923544c49a2273 100644
--- a/third_party/blink/renderer/core/BUILD.gn
+++ b/third_party/blink/renderer/core/BUILD.gn
@@ -330,6 +330,7 @@ component("core") {
   configs -= core_config_remove
   configs += core_config_add
   configs += [ "//v8:external_startup_data" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":buildflags",
diff --git a/third_party/blink/renderer/core/editing/build.gni b/third_party/blink/renderer/core/editing/build.gni
index f12dd0a759fd8a79e648e14711274ccc40642a3d..63ae0ca4f63e68913c809b9440a922a95e914dcd 100644
--- a/third_party/blink/renderer/core/editing/build.gni
+++ b/third_party/blink/renderer/core/editing/build.gni
@@ -354,10 +354,14 @@ blink_core_sources_editing = [
 if (is_mac) {
   blink_core_sources_editing += [
     "commands/smart_replace_cf.cc",
-    "kill_ring_mac.mm",
     "substring_util.h",
     "substring_util.mm",
   ]
+  if (is_mas_build) {
+    blink_core_sources_editing += [ "kill_ring_mac.mm" ]
+  } else {
+    blink_core_sources_editing += [ "kill_ring_none.cc" ]
+  }
 } else {
   blink_core_sources_editing += [ "kill_ring_none.cc" ]
 }
diff --git a/ui/accelerated_widget_mac/BUILD.gn b/ui/accelerated_widget_mac/BUILD.gn
index 3ead42e14ad9d41a30c5637678a3ac49296ce2a6..8dec61ee6a62e54ec3c8c5dd5e08601c28d04dfe 100644
--- a/ui/accelerated_widget_mac/BUILD.gn
+++ b/ui/accelerated_widget_mac/BUILD.gn
@@ -33,6 +33,8 @@ component("accelerated_widget_mac") {
     "QuartzCore.framework",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   if (is_ios) {
     sources += [ "ca_layer_frame_sink_provider.h" ]
   }
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
index b11c365f42dd1ddc363de0d94c387b13ac65bef3..c274340cac7aaf22321b9cd35a8fad2c6eeae5ce 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
@@ -14,7 +14,9 @@
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/presenter.h"
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
@@ -110,7 +112,9 @@ class ACCELERATED_WIDGET_MAC_EXPORT CALayerTreeCoordinator {
   // both the current tree and the pending trees.
   size_t presented_ca_layer_trees_max_length_ = 2;
 
+#if !IS_MAS_BUILD()
   CAContext* __strong ca_context_;
+#endif
 
   // The root CALayer to display the current frame. This does not change
   // over the lifetime of the object.
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
index b99461d52e3a62b58330691e65f9956748cfbf02..09abf39af3e7115744778c7260a68f13a080b162 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
@@ -33,6 +33,7 @@
       new_presentation_feedback_timestamps_(
           new_presentation_feedback_timestamps),
       buffer_presented_callback_(buffer_presented_callback) {
+#if !IS_MAS_BUILD()
   if (allow_remote_layers_) {
     root_ca_layer_ = [[CALayer alloc] init];
 #if BUILDFLAG(IS_MAC)
@@ -61,6 +62,7 @@
 #endif
     ca_context_.layer = root_ca_layer_;
   }
+#endif
 }
 
 CALayerTreeCoordinator::~CALayerTreeCoordinator() = default;
@@ -164,9 +166,13 @@
     TRACE_EVENT_INSTANT2("test_gpu", "SwapBuffers", TRACE_EVENT_SCOPE_THREAD,
                          "GLImpl", static_cast<int>(gl::GetGLImplementation()),
                          "width", pixel_size_.width());
+#if !IS_MAS_BUILD()
     if (allow_remote_layers_) {
       params.ca_context_id = [ca_context_ contextId];
     } else {
+#else
+    if (true) {
+#endif
       IOSurfaceRef io_surface = frame->layer_tree->GetContentIOSurface();
       if (io_surface) {
         DCHECK(!allow_remote_layers_);
diff --git a/ui/accelerated_widget_mac/display_ca_layer_tree.mm b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
index dcf493d62990018040a3f84b6f875af737bd2214..6ffffe8b3946e0427aead8be19878c537c841294 100644
--- a/ui/accelerated_widget_mac/display_ca_layer_tree.mm
+++ b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
@@ -121,6 +121,7 @@ - (void)setContentsChanged;
 }
 
 void DisplayCALayerTree::GotCALayerFrame(uint32_t ca_context_id) {
+#if !IS_MAS_BUILD()
   // Early-out if the remote layer has not changed.
   if (remote_layer_.contextId == ca_context_id) {
     return;
@@ -150,6 +151,9 @@ - (void)setContentsChanged;
     [io_surface_layer_ removeFromSuperlayer];
     io_surface_layer_ = nil;
   }
+#else
+  NOTREACHED() << "Remote layer is being used in MAS build";
+#endif
 }
 
 void DisplayCALayerTree::GotIOSurfaceFrame(
diff --git a/ui/accessibility/platform/BUILD.gn b/ui/accessibility/platform/BUILD.gn
index 3e295499c9ddf8fbb4376e711c57855c8df5e451..c90568d1f5f67ca3e1510aafb524b99c098c455e 100644
--- a/ui/accessibility/platform/BUILD.gn
+++ b/ui/accessibility/platform/BUILD.gn
@@ -254,6 +254,7 @@ component("platform") {
       weak_frameworks = [
         "Accessibility.framework",  # macOS 11
       ]
+      configs += ["//electron/build/config:mas_build"]
     }
 
     if (is_ios) {
diff --git a/ui/accessibility/platform/inspect/ax_transform_mac.mm b/ui/accessibility/platform/inspect/ax_transform_mac.mm
index 84e156b7ff28abc2071dde155e56a2a92a53b142..bd73dac7fe3ed256cab805a0815d31d4f5e7dffc 100644
--- a/ui/accessibility/platform/inspect/ax_transform_mac.mm
+++ b/ui/accessibility/platform/inspect/ax_transform_mac.mm
@@ -108,6 +108,7 @@
     }
   }
 
+#if !IS_MAS_BUILD()
   // AXTextMarker
   if (IsAXTextMarker(value)) {
     return AXTextMarkerToBaseValue(value, indexer);
@@ -117,6 +118,7 @@
   if (IsAXTextMarkerRange(value)) {
     return AXTextMarkerRangeToBaseValue(value, indexer);
   }
+#endif
 
   // Accessible object
   if (AXElementWrapper::IsValidElement(value)) {
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 70342aaf70db9d0d53494ea98c4eec5e36c58de5..ecf8c102cbb6110eabeba95053a2fdfb739c954c 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -363,6 +363,7 @@ component("base") {
       "interaction/element_tracker_mac.mm",
       "resource/resource_bundle_mac.mm",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_apple) {
@@ -380,6 +381,13 @@ component("base") {
     sources += [ "resource/resource_bundle_lacros.cc" ]
   }
 
+  if (is_mas_build) {
+    sources -= [
+      "cocoa/remote_accessibility_api.h",
+      "cocoa/remote_accessibility_api.mm",
+    ]
+  }
+
   if (is_ios) {
     sources += [
       "device_form_factor_ios.mm",
diff --git a/ui/base/cocoa/remote_accessibility_api.h b/ui/base/cocoa/remote_accessibility_api.h
index 3182458838aa96d34911280ab4c6c3aa4aa22d6d..17b57f54492421743a0d69106eefce2c9beb8e87 100644
--- a/ui/base/cocoa/remote_accessibility_api.h
+++ b/ui/base/cocoa/remote_accessibility_api.h
@@ -13,6 +13,8 @@
 
 // NSAccessibilityRemoteUIElement is a private class in AppKit.
 
+#if !IS_MAS_BUILD()
+
 @interface NSAccessibilityRemoteUIElement : NSObject
 + (void)setRemoteUIApp:(BOOL)flag;
 + (BOOL)isRemoteUIApp;
@@ -38,4 +40,6 @@ class COMPONENT_EXPORT(UI_BASE) RemoteAccessibility {
 
 }  // namespace ui
 
+#endif  // MAS_BUILD
+
 #endif  // UI_BASE_COCOA_REMOTE_ACCESSIBILITY_API_H_
diff --git a/ui/base/cocoa/remote_layer_api.h b/ui/base/cocoa/remote_layer_api.h
index 59dc2f82214cfd883b6ebef3b0fb25af6387a9cd..d585ba14b34021a93c878d0d9f9d9ef70eed32ca 100644
--- a/ui/base/cocoa/remote_layer_api.h
+++ b/ui/base/cocoa/remote_layer_api.h
@@ -17,6 +17,7 @@
 
 #if BUILDFLAG(IS_MAC)
 
+#if !IS_MAS_BUILD()
 // The CGSConnectionID is used to create the CAContext in the process that is
 // going to share the CALayers that it is rendering to another process to
 // display.
@@ -68,6 +69,8 @@ extern NSString* const kCAContextIgnoresHitTest;
 
 #endif  // __OBJC__
 
+#endif // MAS_BUILD
+
 namespace ui {
 
 // This function will check if all of the interfaces listed above are supported
diff --git a/ui/base/cocoa/remote_layer_api.mm b/ui/base/cocoa/remote_layer_api.mm
index fc25ba79d2b0e1acdb7ba54b89e7d6e16f94771b..962df2d65d61ec0836cf465d847eb666033846f2 100644
--- a/ui/base/cocoa/remote_layer_api.mm
+++ b/ui/base/cocoa/remote_layer_api.mm
@@ -10,6 +10,7 @@
 
 namespace ui {
 
+#if !IS_MAS_BUILD()
 namespace {
 // Control use of cross-process CALayers to display content directly from the
 // GPU process on Mac.
@@ -17,8 +18,10 @@
              "RemoteCoreAnimationAPI",
              base::FEATURE_ENABLED_BY_DEFAULT);
 }  // namespace
+#endif
 
 bool RemoteLayerAPISupported() {
+#if !IS_MAS_BUILD()
   if (!base::FeatureList::IsEnabled(kRemoteCoreAnimationAPI))
     return false;
 
@@ -55,6 +58,9 @@ bool RemoteLayerAPISupported() {
 
   // If everything is there, we should be able to use the API.
   return true;
+#else
+  return false;
+#endif  // MAS_BUILD
 }
 
 }  // namespace
diff --git a/ui/display/BUILD.gn b/ui/display/BUILD.gn
index 761d9361972720855719ae3418e19c623c465361..752744e489b9b2c184012562985e7803ef685b17 100644
--- a/ui/display/BUILD.gn
+++ b/ui/display/BUILD.gn
@@ -69,6 +69,10 @@ component("display") {
       "mac/display_link_mac.h",
       "mac/screen_mac.mm",
     ]
+
+    configs += [
+      "//electron/build/config:mas_build"
+    ]
   }
 
   if (is_win) {
diff --git a/ui/display/mac/screen_mac.mm b/ui/display/mac/screen_mac.mm
index cd08cb3b7c95a8fd418524652bb345945291112a..13c6cc142262781450d1075fe85f86ada3f9f60f 100644
--- a/ui/display/mac/screen_mac.mm
+++ b/ui/display/mac/screen_mac.mm
@@ -171,7 +171,17 @@ DisplayMac BuildDisplayForScreen(NSScreen* screen) {
     display.set_color_depth(Display::kDefaultBitsPerPixel);
     display.set_depth_per_component(Display::kDefaultBitsPerComponent);
   }
+#if IS_MAS_BUILD()
+  // This is equivalent to the CGDisplayUsesForceToGray() API as at 2018-08-06,
+  // but avoids usage of the private API.
+  CFStringRef app = CFSTR("com.apple.CoreGraphics");
+  CFStringRef key = CFSTR("DisplayUseForcedGray");
+  Boolean key_valid = false;
+  display.set_is_monochrome(
+      CFPreferencesGetAppBooleanValue(key, app, &key_valid));
+#else
   display.set_is_monochrome(CGDisplayUsesForceToGray());
+#endif
 
   // Query the display's refresh rate.
   {
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index 060744da5ed7e6d814a94b2b8576ff672c980c85..0cdd00f78c1518e29bc935e4b35399091882de71 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -204,6 +204,7 @@ component("gfx") {
       "scoped_ns_graphics_context_save_gstate_mac.h",
       "scoped_ns_graphics_context_save_gstate_mac.mm",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
   if (is_win) {
     sources += [
diff --git a/ui/gfx/platform_font_mac.mm b/ui/gfx/platform_font_mac.mm
index 0ab5fbd2a81d8860c73f29c08896f6755b5ca5fa..9400c6c7698258ff2834c550fb8901b49ced35bd 100644
--- a/ui/gfx/platform_font_mac.mm
+++ b/ui/gfx/platform_font_mac.mm
@@ -28,9 +28,11 @@
 
 using Weight = Font::Weight;
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CTFontDescriptorIsSystemUIFont(CTFontDescriptorRef);
 }
+#endif
 
 namespace {
 
@@ -245,7 +247,13 @@ CTFontRef SystemFontForConstructorOfType(PlatformFontMac::SystemFontType type) {
   // TODO(avi, etienneb): Figure out this font stuff.
   base::apple::ScopedCFTypeRef<CTFontDescriptorRef> descriptor(
       CTFontCopyFontDescriptor(font));
+#if IS_MAS_BUILD()
+  CFNumberRef priority = (CFNumberRef)CTFontDescriptorCopyAttribute(descriptor.get(), (CFStringRef)kCTFontPriorityAttribute);
+  SInt64 v;
+  if (CFNumberGetValue(priority, kCFNumberSInt64Type, &v) && v == kCTFontPrioritySystem) {
+#else
   if (CTFontDescriptorIsSystemUIFont(descriptor.get())) {
+#endif
     // Assume it's the standard system font. The fact that this much is known is
     // enough.
     return PlatformFontMac::SystemFontType::kGeneral;
diff --git a/ui/views/BUILD.gn b/ui/views/BUILD.gn
index a14ebf37508ab6e419507c41536689052d52439c..60cb9b1df27453103649deb4f6a6e26b4c9e3c89 100644
--- a/ui/views/BUILD.gn
+++ b/ui/views/BUILD.gn
@@ -716,6 +716,7 @@ component("views") {
       "IOSurface.framework",
       "QuartzCore.framework",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_win) {
@@ -1145,6 +1146,8 @@ source_set("test_support") {
     "//testing/gtest",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   if (is_win) {
     sources += [
       "test/desktop_window_tree_host_win_test_api.cc",
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.h b/ui/views/cocoa/native_widget_mac_ns_window_host.h
index 06cb52062e66fc27c00941e703b909cf42cfa322..309f7a351b8a2aa2ccc42a084a5af086ddb8691d 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.h
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.h
@@ -30,7 +30,9 @@
 #include "ui/views/window/dialog_observer.h"
 
 @class NativeWidgetMacNSWindow;
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class NSView;
 
 namespace remote_cocoa {
@@ -465,10 +467,12 @@ class VIEWS_EXPORT NativeWidgetMacNSWindowHost
   mojo::AssociatedRemote<remote_cocoa::mojom::NativeWidgetNSWindow>
       remote_ns_window_remote_;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow and its root
   // NSView.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
   NSAccessibilityRemoteUIElement* __strong remote_view_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // views::Views accessibility tree when the NSView for this is focused.
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.mm b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
index b50e6f05254ea9e12985fa18b5468c3c020cf3cf..43051bb6a54ed56b2f920555f096494e1a5a65a8 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.mm
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
@@ -345,7 +345,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
 NativeWidgetMacNSWindowHost::GetNativeViewAccessibleForNSView() const {
   if (in_process_ns_window_bridge_)
     return in_process_ns_window_bridge_->ns_view();
+#if !IS_MAS_BUILD()
   return remote_view_accessible_;
+#else
+  return nullptr;
+#endif
 }
 
 gfx::NativeViewAccessible
@@ -360,7 +364,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
     return [in_process_ns_window_bridge_->ns_view() window];
   }
 
+#if !IS_MAS_BUILD()
   return remote_window_accessible_;
+#else
+  return nullptr;
+#endif
 }
 
 remote_cocoa::mojom::NativeWidgetNSWindow*
@@ -1265,9 +1273,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   // for PWAs. However this breaks accessibility on in-process windows,
   // so set it back to NO when a local window gains focus. See
   // https://crbug.com/41485830.
+#if !IS_MAS_BUILD()
   if (is_key && features::IsAccessibilityRemoteUIAppEnabled()) {
     [NSAccessibilityRemoteUIElement setRemoteUIApp:!!application_host_];
   }
+#endif
   // Explicitly set the keyboard accessibility state on regaining key
   // window status.
   if (is_key && is_content_first_responder)
@@ -1420,17 +1430,20 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
 void NativeWidgetMacNSWindowHost::SetRemoteAccessibilityTokens(
     const std::vector<uint8_t>& window_token,
     const std::vector<uint8_t>& view_token) {
+#if !IS_MAS_BUILD()
   remote_window_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   remote_view_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(view_token);
   [remote_view_accessible_ setWindowUIElement:remote_window_accessible_];
   [remote_view_accessible_ setTopLevelUIElement:remote_window_accessible_];
+#endif
 }
 
 bool NativeWidgetMacNSWindowHost::GetRootViewAccessibilityToken(
     base::ProcessId* pid,
     std::vector<uint8_t>* token) {
+#if !IS_MAS_BUILD()
   *pid = getpid();
   id element_id = GetNativeViewAccessible();
 
@@ -1443,6 +1456,7 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   }
 
   *token = ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
+#endif
   return true;
 }
 
diff --git a/ui/views/controls/webview/BUILD.gn b/ui/views/controls/webview/BUILD.gn
index 111d6432586f47833dde50678b908c76ad88d37a..45601d06f85ba618fe38c96ae28c47d306784e53 100644
--- a/ui/views/controls/webview/BUILD.gn
+++ b/ui/views/controls/webview/BUILD.gn
@@ -19,6 +19,9 @@ component("webview") {
 
   if (is_mac) {
     sources += [ "unhandled_keyboard_event_handler_mac.mm" ]
+    configs += [
+      "//electron/build/config:mas_build",
+    ]
   }
 
   if (is_win) {
