Make <webview> use out-of-process iframe architecture.

extensions/browser/guest_view/extensions_guest_view_message_filter.cc

Index: extensions/browser/guest_view/extensions_guest_view_message_filter.cc
diff --git a/extensions/browser/guest_view/extensions_guest_view_message_filter.cc b/extensions/browser/guest_view/extensions_guest_view_message_filter.cc
index 1d6f6605e0ca67c5d77e3a5b57d59e7ead7d573c..dd0eb24de8a9feb6380332ca9beec8cf546b7873 100644
--- a/extensions/browser/guest_view/extensions_guest_view_message_filter.cc
+++ b/extensions/browser/guest_view/extensions_guest_view_message_filter.cc
@@ -46,6 +46,7 @@ void ExtensionsGuestViewMessageFilter::OverrideThreadForMessage(
     const IPC::Message& message,
     BrowserThread::ID* thread) {
   switch (message.type()) {
+    case ExtensionsGuestViewHostMsg_AttachToEmbedderFrame::ID:
     case ExtensionsGuestViewHostMsg_CreateMimeHandlerViewGuest::ID:
     case ExtensionsGuestViewHostMsg_ResizeGuest::ID:
       *thread = BrowserThread::UI;
@@ -65,6 +66,8 @@ bool ExtensionsGuestViewMessageFilter::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(ExtensionsGuestViewMessageFilter, message)
+  IPC_MESSAGE_HANDLER(ExtensionsGuestViewHostMsg_AttachToEmbedderFrame,
+                      OnAttachToEmbedderFrame)
     IPC_MESSAGE_HANDLER(ExtensionsGuestViewHostMsg_CanExecuteContentScriptSync,
                         OnCanExecuteContentScript)
     IPC_MESSAGE_HANDLER(ExtensionsGuestViewHostMsg_CreateMimeHandlerViewGuest,
@@ -75,6 +78,26 @@ bool ExtensionsGuestViewMessageFilter::OnMessageReceived(
   return handled;
 }
 
+void ExtensionsGuestViewMessageFilter::OnAttachToEmbedderFrame(
+    int embedder_local_render_frame_id,
+    int element_instance_id,
+    int guest_instance_id) {
+  auto manager = GuestViewManager::FromBrowserContext(browser_context_);
+  DCHECK(manager);
+  content::WebContents* guest_web_contents =
+      manager->GetGuestByInstanceIDHack(guest_instance_id);
+  DCHECK(guest_web_contents);
+  auto guest = WebViewGuest::FromWebContents(guest_web_contents);
+  DCHECK(guest);
+  content::WebContents* owner_web_contents = guest->owner_web_contents();
+  DCHECK(owner_web_contents);
+  auto embedder_frame = RenderFrameHost::FromID(render_process_id_,
+                                                embedder_local_render_frame_id);
+  guest_web_contents->AttachToEmbedderFrame(owner_web_contents, embedder_frame);
+  owner_web_contents->GetMainFrame()->Send(
+      new ExtensionsGuestViewMsg_ContentWindowReady(element_instance_id));
+}
+
 void ExtensionsGuestViewMessageFilter::OnCanExecuteContentScript(
     int render_view_id,
     int script_id,