Make RenderFrame(Host) own a RenderWidget(Host).

content/browser/renderer_host/render_widget_host_impl.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 172 matching lines @@
 
   int surface_id() const { return surface_id_; }
 
   bool empty() const { return current_size_.IsEmpty(); }
 
   // Called when a renderer object already been created for this host, and we
   // just need to be attached to it. Used for window.open, <select> dropdown
   // menus, and other times when the renderer initiates creating an object.
   virtual void Init();
 
+  // Initializes a RenderWidgetHost that is attached to a Frame.
+  virtual void InitForFrame();

[nasko, 2014/12/17 22:51:30]

Why is this one virtual?

[kenrb, 2015/01/05 21:15:30]

No reason. Fixed.

+
   // Tells the renderer to die and then calls Destroy().
   virtual void Shutdown();
 
   // IPC::Listener
   bool OnMessageReceived(const IPC::Message& msg) override;
 
   // Sends a message to the corresponding object in the renderer.
   bool Send(IPC::Message* msg) override;
 
   // Indicates if the page has finished loading.
@@ skipping 630 matching lines @@
   PendingSnapshotMap pending_browser_snapshots_;
 
   base::WeakPtrFactory<RenderWidgetHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_