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

content/common/frame_messages.h

 // Copyright 2013 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.
 
 // IPC messages for interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/common/frame_message_enums.h"
@@ skipping 354 matching lines @@
 // Requests that the RenderFrame or RenderFrameProxy sets its opener to null.
 IPC_MESSAGE_ROUTED0(FrameMsg_DisownOpener)
 
 // Instructs the renderer to create a new RenderFrame object with |routing_id|.
 // The new frame should be created as a child of the object identified by
 // |parent_routing_id| or as top level if that is MSG_ROUTING_NONE.
 IPC_MESSAGE_CONTROL2(FrameMsg_NewFrame,
                      int /* routing_id */,
                      int /* parent_routing_id */)
 
+IPC_MESSAGE_ROUTED2(FrameMsg_NewWidgetForFrame,
+                    int /* routing_id_for_widget */,
+                    bool /* hidden */)
+
 // Instructs the renderer to create a new RenderFrameProxy object with
 // |routing_id|. The new proxy should be created as a child of the object
 // identified by |parent_routing_id| or as top level if that is
 // MSG_ROUTING_NONE.
 IPC_MESSAGE_CONTROL3(FrameMsg_NewFrameProxy,
                      int /* routing_id */,
                      int /* parent_routing_id */,
                      int /* render_view_routing_id */)
 
 // Tells the renderer to perform the specified navigation, interrupting any
@@ skipping 368 matching lines @@
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidFirstVisuallyNonEmptyPaint)
 
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
 
 // Message to show/hide a popup menu using native controls.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ShowPopup,
                     FrameHostMsg_ShowPopup_Params)
 IPC_MESSAGE_ROUTED0(FrameHostMsg_HidePopup)
 
 #endif