fix: revert "refactor: only create webContents after 'will-attach-webview'… (#31848)

* Revert "refactor: only create webContents after 'will-attach-webview' (#30311)" (#31785)

This reverts commit 6e43b0bcbf17667e826bb64b551cb16e3f8bd9b9.

* fix: backport 31785 to fix localStorage persistence regression

lib/browser/guest-view-manager.ts

@@ -7,7 +7,7 @@ import { webViewEvents } from '@electron/internal/common/web-view-events';
 import { IPC_MESSAGES } from '@electron/internal/common/ipc-messages';
 
 interface GuestInstance {
-  elementInstanceId: number;
+  elementInstanceId?: number;
   visibilityState?: VisibilityState;
   embedder: Electron.WebContents;
   guest: Electron.WebContents;
@@ -45,7 +45,6 @@ function makeWebPreferences (embedder: Electron.WebContents, params: Record<stri
     webSecurity: !params.disablewebsecurity,
     enableBlinkFeatures: params.blinkfeatures,
     disableBlinkFeatures: params.disableblinkfeatures,
-    partition: params.partition,
     ...parsedWebPreferences
   };
 
@@ -77,24 +76,14 @@ function makeWebPreferences (embedder: Electron.WebContents, params: Record<stri
 
 // Create a new guest instance.
 const createGuest = function (embedder: Electron.WebContents, embedderFrameId: number, elementInstanceId: number, params: Record<string, any>) {
-  const webPreferences = makeWebPreferences(embedder, params);
-  const event = eventBinding.createWithSender(embedder);
-
-  embedder.emit('will-attach-webview', event, webPreferences, params);
-  if (event.defaultPrevented) {
-    return -1;
-  }
-
   // eslint-disable-next-line no-undef
   const guest = (webContents as typeof ElectronInternal.WebContents).create({
-    ...webPreferences,
     type: 'webview',
+    partition: params.partition,
     embedder
   });
-
   const guestInstanceId = guest.id;
   guestInstances.set(guestInstanceId, {
-    elementInstanceId,
     guest,
     embedder
   });
@@ -108,6 +97,9 @@ const createGuest = function (embedder: Electron.WebContents, embedderFrameId: n
 
   // Init guest web view after attached.
   guest.once('did-attach' as any, function (this: Electron.WebContents, event: Electron.Event) {
+    params = this.attachParams!;
+    delete this.attachParams;
+
     const previouslyAttached = this.viewInstanceId != null;
     this.viewInstanceId = params.instanceId;
 
@@ -177,25 +169,76 @@ const createGuest = function (embedder: Electron.WebContents, embedderFrameId: n
     }
   });
 
+  if (attachGuest(embedder, embedderFrameId, elementInstanceId, guestInstanceId, params)) {
+    return guestInstanceId;
+  }
+
+  return -1;
+};
+
+// Attach the guest to an element of embedder.
+const attachGuest = function (embedder: Electron.WebContents, embedderFrameId: number, elementInstanceId: number, guestInstanceId: number, params: Record<string, any>) {
   // Destroy the old guest when attaching.
   const key = `${embedder.id}-${elementInstanceId}`;
   const oldGuestInstanceId = embedderElementsMap.get(key);
   if (oldGuestInstanceId != null) {
+    // Reattachment to the same guest is just a no-op.
+    if (oldGuestInstanceId === guestInstanceId) {
+      return false;
+    }
+
     const oldGuestInstance = guestInstances.get(oldGuestInstanceId);
     if (oldGuestInstance) {
       oldGuestInstance.guest.detachFromOuterFrame();
     }
   }
 
+  const guestInstance = guestInstances.get(guestInstanceId);
+  // If this isn't a valid guest instance then do nothing.
+  if (!guestInstance) {
+    console.error(new Error(`Guest attach failed: Invalid guestInstanceId ${guestInstanceId}`));
+    return false;
+  }
+  const { guest } = guestInstance;
+  if (guest.hostWebContents !== embedder) {
+    console.error(new Error(`Guest attach failed: Access denied to guestInstanceId ${guestInstanceId}`));
+    return false;
+  }
+
+  // If this guest is already attached to an element then remove it
+  if (guestInstance.elementInstanceId) {
+    const oldKey = `${guestInstance.embedder.id}-${guestInstance.elementInstanceId}`;
+    embedderElementsMap.delete(oldKey);
+
+    // Remove guest from embedder if moving across web views
+    if (guest.viewInstanceId !== params.instanceId) {
+      webViewManager.removeGuest(guestInstance.embedder, guestInstanceId);
+      guestInstance.embedder._sendInternal(`${IPC_MESSAGES.GUEST_VIEW_INTERNAL_DESTROY_GUEST}-${guest.viewInstanceId}`);
+    }
+  }
+
+  const webPreferences = makeWebPreferences(embedder, params);
+
+  const event = eventBinding.createWithSender(embedder);
+  embedder.emit('will-attach-webview', event, webPreferences, params);
+  if (event.defaultPrevented) {
+    if (guest.viewInstanceId == null) guest.viewInstanceId = params.instanceId;
+    guest.destroy();
+    return false;
+  }
+
+  guest.attachParams = params;
   embedderElementsMap.set(key, guestInstanceId);
+
   guest.setEmbedder(embedder);
+  guestInstance.embedder = embedder;
+  guestInstance.elementInstanceId = elementInstanceId;
 
   watchEmbedder(embedder);
 
   webViewManager.addGuest(guestInstanceId, embedder, guest, webPreferences);
   guest.attachToIframe(embedder, embedderFrameId);
-
-  return guestInstanceId;
+  return true;
 };
 
 // Remove an guest-embedder relationship.

lib/common/ipc-messages.ts

@@ -8,6 +8,7 @@ export const enum IPC_MESSAGES {
 
   GUEST_INSTANCE_VISIBILITY_CHANGE = 'GUEST_INSTANCE_VISIBILITY_CHANGE',
 
+  GUEST_VIEW_INTERNAL_DESTROY_GUEST = 'GUEST_VIEW_INTERNAL_DESTROY_GUEST',
   GUEST_VIEW_INTERNAL_DISPATCH_EVENT = 'GUEST_VIEW_INTERNAL_DISPATCH_EVENT',
 
   GUEST_VIEW_MANAGER_CREATE_AND_ATTACH_GUEST = 'GUEST_VIEW_MANAGER_CREATE_AND_ATTACH_GUEST',

lib/renderer/web-view/guest-view-internal.ts

@@ -6,6 +6,7 @@ const { mainFrame: webFrame } = process._linkedBinding('electron_renderer_web_fr
 
 export interface GuestViewDelegate {
   dispatchEvent (eventName: string, props: Record<string, any>): void;
+  reset(): void;
 }
 
 const DEPRECATED_EVENTS: Record<string, string> = {
@@ -13,6 +14,11 @@ const DEPRECATED_EVENTS: Record<string, string> = {
 } as const;
 
 export function registerEvents (viewInstanceId: number, delegate: GuestViewDelegate) {
+  ipcRendererInternal.on(`${IPC_MESSAGES.GUEST_VIEW_INTERNAL_DESTROY_GUEST}-${viewInstanceId}`, function () {
+    delegate.reset();
+    delegate.dispatchEvent('destroyed', {});
+  });
+
   ipcRendererInternal.on(`${IPC_MESSAGES.GUEST_VIEW_INTERNAL_DISPATCH_EVENT}-${viewInstanceId}`, function (event, eventName, props) {
     if (DEPRECATED_EVENTS[eventName] != null) {
       delegate.dispatchEvent(DEPRECATED_EVENTS[eventName], props);
@@ -23,6 +29,7 @@ export function registerEvents (viewInstanceId: number, delegate: GuestViewDeleg
 }
 
 export function deregisterEvents (viewInstanceId: number) {
+  ipcRendererInternal.removeAllListeners(`${IPC_MESSAGES.GUEST_VIEW_INTERNAL_DESTROY_GUEST}-${viewInstanceId}`);
   ipcRendererInternal.removeAllListeners(`${IPC_MESSAGES.GUEST_VIEW_INTERNAL_DISPATCH_EVENT}-${viewInstanceId}`);
 }
 

lib/renderer/web-view/web-view-element.ts

@@ -55,7 +55,8 @@ const defineWebViewElement = (hooks: WebViewImplHooks) => {
       }
       if (!internal.elementAttached) {
         hooks.guestViewInternal.registerEvents(internal.viewInstanceId, {
-          dispatchEvent: internal.dispatchEvent.bind(internal)
+          dispatchEvent: internal.dispatchEvent.bind(internal),
+          reset: internal.reset.bind(internal)
         });
         internal.elementAttached = true;
         (internal.attributes.get(WEB_VIEW_CONSTANTS.ATTRIBUTE_SRC) as SrcAttribute).parse();

lib/renderer/web-view/web-view-impl.ts

@@ -193,7 +193,7 @@ export class WebViewImpl {
 
   attachGuestInstance (guestInstanceId: number) {
     if (guestInstanceId === -1) {
-      this.dispatchEvent('destroyed');
+      // Do nothing
       return;
     }
 

shell/browser/api/electron_api_web_view_manager.cc

@@ -28,6 +28,10 @@ void AddGuest(int guest_instance_id,
     electron::WebContentsZoomController::FromWebContents(guest_web_contents)
         ->SetDefaultZoomFactor(zoom_factor);
   }
+
+  WebContentsPreferences::From(guest_web_contents)->Merge(options);
+  // Trigger re-calculation of webkit prefs.
+  guest_web_contents->NotifyPreferencesChanged();
 }
 
 void RemoveGuest(content::WebContents* embedder, int guest_instance_id) {

shell/browser/web_contents_preferences.cc

@@ -176,7 +176,11 @@ void WebContentsPreferences::Clear() {
 void WebContentsPreferences::SetFromDictionary(
     const gin_helper::Dictionary& web_preferences) {
   Clear();
+  Merge(web_preferences);
+}
 
+void WebContentsPreferences::Merge(
+    const gin_helper::Dictionary& web_preferences) {
   web_preferences.Get(options::kPlugins, &plugins_);
   web_preferences.Get(options::kExperimentalFeatures, &experimental_features_);
   web_preferences.Get(options::kNodeIntegration, &node_integration_);

shell/browser/web_contents_preferences.h

@@ -36,6 +36,8 @@ class WebContentsPreferences
                          const gin_helper::Dictionary& web_preferences);
   ~WebContentsPreferences() override;
 
+  void Merge(const gin_helper::Dictionary& new_web_preferences);
+
   void SetFromDictionary(const gin_helper::Dictionary& new_web_preferences);
 
   // Append command paramters according to preferences.

typings/internal-electron.d.ts

@@ -80,6 +80,7 @@ declare namespace Electron {
     attachToIframe(embedderWebContents: Electron.WebContents, embedderFrameId: number): void;
     detachFromOuterFrame(): void;
     setEmbedder(embedder: Electron.WebContents): void;
+    attachParams?: Record<string, any>;
     viewInstanceId: number;
   }