feat: add `tabbingIdentifier` property to `BrowserWindow` (#40410)

feat: add tabbingIdentifier property to BrowserWindow

docs/api/browser-window.md

@@ -505,6 +505,10 @@ events.
 
 A `Integer` property representing the unique ID of the window. Each ID is unique among all `BrowserWindow` instances of the entire Electron application.
 
+#### `win.tabbingIdentifier` _macOS_ _Readonly_
+
+A `string` (optional) property that is equal to the `tabbingIdentifier` passed to the `BrowserWindow` constructor or `undefined` if none was set.
+
 #### `win.autoHideMenuBar`
 
 A `boolean` property that determines whether the window menu bar should hide itself automatically. Once set, the menu bar will only show when users press the single `Alt` key.

shell/browser/api/electron_api_base_window.cc

@@ -945,6 +945,14 @@ void BaseWindow::AddTabbedWindow(NativeWindow* window,
     args->ThrowError("AddTabbedWindow cannot be called by a window on itself.");
 }
 
+v8::Local<v8::Value> BaseWindow::GetTabbingIdentifier() {
+  auto tabbing_id = window_->GetTabbingIdentifier();
+  if (!tabbing_id.has_value())
+    return v8::Undefined(isolate());
+
+  return gin::ConvertToV8(isolate(), tabbing_id.value());
+}
+
 void BaseWindow::SetAutoHideMenuBar(bool auto_hide) {
   window_->SetAutoHideMenuBar(auto_hide);
 }
@@ -1296,6 +1304,7 @@ void BaseWindow::BuildPrototype(v8::Isolate* isolate,
       .SetMethod("moveTabToNewWindow", &BaseWindow::MoveTabToNewWindow)
       .SetMethod("toggleTabBar", &BaseWindow::ToggleTabBar)
       .SetMethod("addTabbedWindow", &BaseWindow::AddTabbedWindow)
+      .SetProperty("tabbingIdentifier", &BaseWindow::GetTabbingIdentifier)
       .SetMethod("setWindowButtonVisibility",
                  &BaseWindow::SetWindowButtonVisibility)
       .SetMethod("_getWindowButtonVisibility",

shell/browser/api/electron_api_base_window.h

@@ -198,9 +198,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   bool GetWindowButtonVisibility() const;
   void SetWindowButtonPosition(absl::optional<gfx::Point> position);
   absl::optional<gfx::Point> GetWindowButtonPosition() const;
-#endif
 
-#if BUILDFLAG(IS_MAC)
   bool IsHiddenInMissionControl();
   void SetHiddenInMissionControl(bool hidden);
 #endif
@@ -214,6 +212,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   void MoveTabToNewWindow();
   void ToggleTabBar();
   void AddTabbedWindow(NativeWindow* window, gin_helper::Arguments* args);
+  v8::Local<v8::Value> GetTabbingIdentifier();
   void SetAutoHideMenuBar(bool auto_hide);
   bool IsMenuBarAutoHide();
   void SetMenuBarVisibility(bool visible);

shell/browser/native_window.cc

@@ -454,6 +454,10 @@ bool NativeWindow::AddTabbedWindow(NativeWindow* window) {
 
 void NativeWindow::SetVibrancy(const std::string& type) {}
 
+absl::optional<std::string> NativeWindow::GetTabbingIdentifier() const {
+  return "";  // for non-Mac platforms
+}
+
 void NativeWindow::SetBackgroundMaterial(const std::string& type) {}
 
 void NativeWindow::SetTouchBar(

shell/browser/native_window.h

@@ -250,6 +250,7 @@ class NativeWindow : public base::SupportsUserData,
   virtual void MoveTabToNewWindow();
   virtual void ToggleTabBar();
   virtual bool AddTabbedWindow(NativeWindow* window);
+  virtual absl::optional<std::string> GetTabbingIdentifier() const;
 
   // Toggle the menu bar.
   virtual void SetAutoHideMenuBar(bool auto_hide);

shell/browser/native_window_mac.h

@@ -143,6 +143,7 @@ class NativeWindowMac : public NativeWindow,
   void MoveTabToNewWindow() override;
   void ToggleTabBar() override;
   bool AddTabbedWindow(NativeWindow* window) override;
+  absl::optional<std::string> GetTabbingIdentifier() const override;
   void SetAspectRatio(double aspect_ratio,
                       const gfx::Size& extra_size) override;
   void PreviewFile(const std::string& path,

shell/browser/native_window_mac.mm

@@ -1675,6 +1675,13 @@ bool NativeWindowMac::AddTabbedWindow(NativeWindow* window) {
   return true;
 }
 
+absl::optional<std::string> NativeWindowMac::GetTabbingIdentifier() const {
+  if ([window_ tabbingMode] == NSWindowTabbingModeDisallowed)
+    return absl::nullopt;
+
+  return base::SysNSStringToUTF8([window_ tabbingIdentifier]);
+}
+
 void NativeWindowMac::SetAspectRatio(double aspect_ratio,
                                      const gfx::Size& extra_size) {
   NativeWindow::SetAspectRatio(aspect_ratio, extra_size);

spec/api-browser-window-spec.ts

@@ -2067,10 +2067,7 @@ describe('BrowserWindow module', () => {
     beforeEach(() => {
       w = new BrowserWindow({ show: false });
     });
-    afterEach(async () => {
-      await closeWindow(w);
-      w = null as unknown as BrowserWindow;
-    });
+    afterEach(closeAllWindows);
 
     describe('BrowserWindow.selectPreviousTab()', () => {
       it('does not throw', () => {
@@ -2131,6 +2128,18 @@ describe('BrowserWindow module', () => {
         }).to.throw('AddTabbedWindow cannot be called by a window on itself.');
       });
     });
+
+    describe('BrowserWindow.tabbingIdentifier', () => {
+      it('is undefined if no tabbingIdentifier was set', () => {
+        const w = new BrowserWindow({ show: false });
+        expect(w.tabbingIdentifier).to.be.undefined('tabbingIdentifier');
+      });
+
+      it('returns the window tabbingIdentifier', () => {
+        const w = new BrowserWindow({ show: false, tabbingIdentifier: 'group1' });
+        expect(w.tabbingIdentifier).to.equal('group1');
+      });
+    });
   });
 
   describe('autoHideMenuBar state', () => {