Always create FrameTreeNodes and RenderFrameHosts for every frame.

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/public/common/common_param_traits.h"
 #include "ipc/ipc_message_macros.h"
+#include "url/gurl.h"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 
 #define IPC_MESSAGE_START FrameMsgStart
 
 // Sent by the renderer when a child frame is created in the renderer. The
 // |parent_frame_id| and |frame_id| are NOT routing ids. They are
 // renderer-allocated identifiers used for tracking a frame's creation.
 //
@@ skipping 57 matching lines @@
 // create a plugin.  The browser will create the plugin process if
 // necessary, and will return a handle to the channel on success.
 // On error an empty string is returned.
 IPC_SYNC_MESSAGE_CONTROL4_2(FrameHostMsg_OpenChannelToPlugin,
                             int /* render_frame_id */,
                             GURL /* url */,
                             GURL /* page_url */,
                             std::string /* mime_type */,
                             IPC::ChannelHandle /* channel_handle */,
                             content::WebPluginInfo /* info */)