Prepare RenderFrameProxy for mirroring the frame tree

content/renderer/render_frame_proxy.h

 // Copyright 2014 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_RENDERER_RENDER_FRAME_PROXY_H_
 #define CONTENT_RENDERER_RENDER_FRAME_PROXY_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
@@ skipping 30 matching lines @@
 // finished executing. It will still be responsible for routing IPC messages
 // which are valid for cross-site interactions between frames.
 // RenderFrameProxy will be deleted when the node in the frame tree is deleted
 // or when navigating the frame causes it to return to this process and a new
 // RenderFrame is created for it.
 class CONTENT_EXPORT RenderFrameProxy
     : public IPC::Listener,
       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;
 
   // IPC handlers
   void OnDeleteProxy();
   void OnChildFrameProcessGone();
   void OnBuffersSwapped(const FrameMsg_BuffersSwapped_Params& params);
   void OnCompositorFrameSwapped(const IPC::Message& message);
 
-  blink::WebFrame* GetWebFrame();
+  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_;
 
-  int routing_id_;
-  int frame_routing_id_;
-  RenderFrameImpl* render_frame_;
-
-  scoped_refptr<ChildFrameCompositingHelper> compositing_helper_;
+  RenderViewImpl* render_view_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameProxy);
 };
 
 }  // namespace
 
 #endif  // CONTENT_RENDERER_RENDER_FRAME_PROXY_H_