Support frame tree propagation between renderers in the same browsing instance.

content/browser/renderer_host/render_view_host_impl.h

Index: content/browser/renderer_host/render_view_host_impl.h
diff --git a/content/browser/renderer_host/render_view_host_impl.h b/content/browser/renderer_host/render_view_host_impl.h
index af0d5d2dd7dc203cdeed00a440deecf2007ab253..bf342a2e9e60a0d0bccccae4c09bb8ce288b6f85 100644
--- a/content/browser/renderer_host/render_view_host_impl.h
+++ b/content/browser/renderer_host/render_view_host_impl.h
@@ -209,6 +209,7 @@ class CONTENT_EXPORT RenderViewHostImpl
       const CustomContextMenuContext& context) OVERRIDE;
   virtual void NotifyMoveOrResizeStarted() OVERRIDE;
   virtual void ReloadFrame() OVERRIDE;
+  virtual const std::string& GetFrameTree() OVERRIDE;
   virtual void SetAltErrorPageURL(const GURL& url) OVERRIDE;
   virtual void SetWebUIProperty(const std::string& name,
                                 const std::string& value) OVERRIDE;
@@ -401,6 +402,12 @@ class CONTENT_EXPORT RenderViewHostImpl
     send_accessibility_updated_notifications_ = send;
   }
 
+  // Updates the frame tree for this RVH and sends an IPC down to the renderer
+  // process to keep them in sync.
+  void UpdateFrameTree(int process_id,

[awong, 2012/08/20 21:56:31]

Note, move this up to under SendOrientatinChangeEvent() so we don't split apart
all the accessibility functions?

[nasko, 2012/08/21 00:34:45]

Done.

+                       int route_id,
+                       const std::string& frame_tree);
+
   const AccessibilityNodeData& accessibility_tree_for_testing() {
     return accessibility_tree_;
   }
@@ -542,6 +549,7 @@ class CONTENT_EXPORT RenderViewHostImpl
   void OnRunFileChooser(const FileChooserParams& params);
   void OnDomOperationResponse(const std::string& json_string,
                               int automation_id);
+  void OnFrameTree(const std::string& frame_tree);
 
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
   void OnMsgShowPopup(const ViewHostMsg_ShowPopup_Params& params);
@@ -637,6 +645,9 @@ class CONTENT_EXPORT RenderViewHostImpl
   // for unit testing.
   bool send_accessibility_updated_notifications_;
 
+  // Serialized frame tree structure for the page displayed by the render view.

[awong, 2012/08/20 21:56:31]

Add something that describes what format this is expected to be in?

[nasko, 2012/08/21 00:34:45]

Done.

+  std::string frame_tree_;
+
   // The most recently received accessibility tree - for unit testing only.
   AccessibilityNodeData accessibility_tree_;