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

extensions/renderer/guest_view/guest_view_container.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/guest_view/guest_view_container.h"
 
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "content/public/renderer/render_view.h"
 #include "extensions/common/guest_view/extensions_guest_view_messages.h"
@@ skipping 32 matching lines @@
       render_frame_(render_frame) {
   render_frame_lifetime_observer_.reset(
       new RenderFrameLifetimeObserver(this, render_frame_));
 }
 
 GuestViewContainer::~GuestViewContainer() {}
 
 // static.
 bool GuestViewContainer::HandlesMessage(const IPC::Message& msg) {
   switch (msg.type()) {
+    case ExtensionsGuestViewMsg_ContentWindowReady::ID:
     case ExtensionsGuestViewMsg_CreateMimeHandlerViewGuestACK::ID:
     case ExtensionsGuestViewMsg_MimeHandlerViewGuestOnLoadCompleted::ID:
     case GuestViewMsg_GuestAttached::ID:
     case GuestViewMsg_GuestDetached::ID:
       return true;
     default:
       return false;
   }
 }
 
 void GuestViewContainer::RenderFrameDestroyed() {
   OnRenderFrameDestroyed();
   render_frame_ = nullptr;
 }
 
 void GuestViewContainer::SetElementInstanceID(int element_instance_id) {
   DCHECK_EQ(element_instance_id_, guestview::kInstanceIDNone);
   element_instance_id_ = element_instance_id;
 }
 
 }  // namespace extensions