Prepare RenderFrameProxy for mirroring the frame tree

content/renderer/render_frame_proxy.h

Index: content/renderer/render_frame_proxy.h
diff --git a/content/renderer/render_frame_proxy.h b/content/renderer/render_frame_proxy.h
index 54c63619290485850f4598cfce1c5526fb4e0b41..43fed899d458423acc4b10ed78ce34665f85001a 100644
--- a/content/renderer/render_frame_proxy.h
+++ b/content/renderer/render_frame_proxy.h
@@ -48,28 +48,50 @@ class CONTENT_EXPORT RenderFrameProxy
       public IPC::Sender,
       NON_EXPORTED_BASE(public blink::WebFrameClient) {
  public:
+  // This method should be used to create a RenderFrameProxy, which will replace
+  // an existing RenderFrame during its cross-process navigation from the
+  // current process to a different one. |routing_id| will be ID of the newly
+  // created RenderFrameProxy. |frame_routing_id| is the ID of the RenderFrame
+  // to replace.
+  static RenderFrameProxy* CreateProxyToReplaceFrame(int routing_id,
+                                                     int frame_routing_id);
+
+  // This method should be used to create a RenderFrameProxy, when there isn't

[dcheng, 2014/07/03 05:58:54]

I don't think this comment is completely accurate. This is used to drive
mirroring, right? So it's not /only/ applicable when another frame is doing a
cross-process navigation; it's needed any time a page is hosted in multiple
processes and another process creates a new subframe.

[ncarter (slow), 2014/07/14 17:35:07]

Done.

+  // an existing RenderFrame. It happens when some other frame in the frame tree
+  // of the document is navigating cross-process and a proxy for the new frame
+  // is needed. |routing_id| will be the ID of the newly created
+  // RenderFrameProxy. |parent_routing_id| is the routing ID of the
+  // RenderFrameProxy to which the new frame is parented.

[dcheng, 2014/07/03 05:58:54]

To a reader, I don't think it's immediately obvious why the parent must always
be a RenderFrameProxy--do we have a comment blob somewhere that explains why
(e.g. all subframes begin their life as a RenderFrame)?

[dcheng, 2014/07/03 05:58:54]

To a reader, I don't think it's immediately obvious why the parent must always
be a RenderFrameProxy--do we have a comment blob somewhere that explains why
(e.g. all subframes begin their life as a RenderFrame)?

[ncarter (slow), 2014/07/14 17:35:07]

Done.

+  // |render_view_routing_id| identifies the RenderView to be associated with
+  // this frame.
   static RenderFrameProxy* CreateFrameProxy(int routing_id,
-                                            int frame_routing_id);
+                                            int parent_routing_id,
+                                            int render_view_routing_id);
 
   // Returns the RenderFrameProxy for the given routing ID.
   static RenderFrameProxy* FromRoutingID(int routing_id);
 
+  // Returns the RenderFrameProxy given a WebFrame.
+  static RenderFrameProxy* FromWebFrame(blink::WebFrame* web_frame);
+
   virtual ~RenderFrameProxy();
 
   // IPC::Sender
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
-  RenderFrameImpl* render_frame() {
-    return render_frame_;
-  }
-
   // Out-of-process child frames receive a signal from RenderWidgetCompositor
   // when a compositor frame has committed.
   void DidCommitCompositorFrame();
 
+  int routing_id() { return routing_id_; }

[dcheng, 2014/07/03 05:58:54]

Out of curiosity, is there a particular reason we omit the const here and
elsewhere?

[ncarter (slow), 2014/07/14 17:35:07]

Done.

+  RenderViewImpl* render_view() { return render_view_; }
+  blink::WebFrame* web_frame() { return web_frame_; }
+
  private:
   RenderFrameProxy(int routing_id, int frame_routing_id);
 
+  void Init(blink::WebFrame* frame, RenderViewImpl* render_view);
+
   // IPC::Listener
   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
 
@@ -79,14 +101,13 @@ class CONTENT_EXPORT RenderFrameProxy
   void OnBuffersSwapped(const FrameMsg_BuffersSwapped_Params& params);
   void OnCompositorFrameSwapped(const IPC::Message& message);
 
-  blink::WebFrame* GetWebFrame();
-
-  int routing_id_;
-  int frame_routing_id_;
-  RenderFrameImpl* render_frame_;
-
+  const int routing_id_;
+  const int frame_routing_id_;
+  blink::WebFrame* web_frame_;

[dcheng, 2014/07/03 05:58:54]

I think these fields could use some comments. Also, theoretically, we're only
going to deal with WebRemoteFrames in RemoteFrameProxy right?

[ncarter (slow), 2014/07/14 17:35:07]

Yes, this will become a WebRemoteFrame in a later patch, but it can't until we
switch over to the #if 0'ed code in the .cc file.

   scoped_refptr<ChildFrameCompositingHelper> compositing_helper_;
 
+  RenderViewImpl* render_view_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderFrameProxy);
 };