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..cc1b7acde08b35c3aa462056ee2ebc24516b007a 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 +78,43 @@ bool ExtensionsGuestViewMessageFilter::OnMessageReceived(
   return handled;
 }
 
+void ExtensionsGuestViewMessageFilter::OnAttachToEmbedderFrame(
+    int embedder_local_render_frame_id,
+    int element_instance_id,
+    int guest_instance_id,
+    const base::DictionaryValue& params) {
+  auto* manager = GuestViewManager::FromBrowserContext(browser_context_);
+  DCHECK(manager);
+  content::WebContents* guest_web_contents =
+      manager->GetGuestByInstanceIDSafely(guest_instance_id,
+                                          render_process_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->AttachToOuterWebContentsFrame(owner_web_contents,
+                                                    embedder_frame);
+
+  manager->AttachGuest(render_process_id_, element_instance_id,
+                       guest_instance_id, params);
+
+  owner_web_contents->GetMainFrame()->Send(
+      new ExtensionsGuestViewMsg_GuestReady(element_instance_id));
+
+  guest->WillAttach(
+      owner_web_contents, element_instance_id, false,
+      base::Bind(&ExtensionsGuestViewMessageFilter::WillAttachCallback, this,
+                 guest));
+}
+
+void ExtensionsGuestViewMessageFilter::WillAttachCallback(
+    extensions::WebViewGuest* guest) {
+  guest->DidAttach(MSG_ROUTING_NONE);
+}
+
 void ExtensionsGuestViewMessageFilter::OnCanExecuteContentScript(
     int render_view_id,
     int script_id,