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

extensions/browser/guest_view/extensions_guest_view_message_filter.h

 // Copyright 2015 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.
 
 #ifndef EXTENSIONS_BROWSER_GUEST_VIEW_EXTENSIONS_GUEST_VIEW_MESSAGE_FILTER_H_
 #define EXTENSIONS_BROWSER_GUEST_VIEW_EXTENSIONS_GUEST_VIEW_MESSAGE_FILTER_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 25 matching lines @@
 
   ~ExtensionsGuestViewMessageFilter() override;
 
   // content::BrowserMessageFilter implementation.
   void OverrideThreadForMessage(const IPC::Message& message,
                                 content::BrowserThread::ID* thread) override;
   void OnDestruct() const override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
   // Message handlers on the UI thread.
+  void OnAttachToEmbedderFrame(int embedder_local_render_frame_id,
+                               int element_instance_id,
+                               int guest_instance_id);
   void OnCanExecuteContentScript(int render_view_id,
                                  int script_id,
                                  bool* allowed);
 
   void OnCreateMimeHandlerViewGuest(int render_frame_id,
                                     const std::string& view_id,
                                     int element_instance_id,
                                     const gfx::Size& element_size);
   void OnResizeGuest(int render_frame_id,
                      int element_instance_id,
@@ skipping 13 matching lines @@
 
   // Weak pointers produced by this factory are bound to the IO thread.
   base::WeakPtrFactory<ExtensionsGuestViewMessageFilter> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionsGuestViewMessageFilter);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_GUEST_VIEW_EXTENSIONS_GUEST_VIEW_MESSAGE_FILTER_H_