Start using RenderFrameProxyHost objects.

content/browser/frame_host/frame_tree.h

Index: content/browser/frame_host/frame_tree.h
diff --git a/content/browser/frame_host/frame_tree.h b/content/browser/frame_host/frame_tree.h
index 67e61a98195e27964629342a09c5044d68cb2b45..7c954d18c644caed90f7d1b92c4407be3d7214c5 100644
--- a/content/browser/frame_host/frame_tree.h
+++ b/content/browser/frame_host/frame_tree.h
@@ -71,6 +71,14 @@ class CONTENT_EXPORT FrameTree {
                                 const std::string& frame_name);
   void RemoveFrame(FrameTreeNode* child);
 
+  // When a new process is being created to render content from a specific site

[Charlie Reis, 2014/07/28 19:24:28]

This is still a bit subtle-- it's assuming that "a new process being created"
implies there's no proxies with |site_instance| yet.  What if the process had
crashed and we're recreating it?

If the code is making an assumption that none of the frames in the tree have a
proxy for |site_instance| yet, we should state that.

[kenrb, 2014/07/28 21:07:20]

Done.

+  // instance, this method walks the entire frame tree and creates a
+  // RenderFrameProxyHost for the given |site_instance| in each node except
+  // the |source| one -- the source will have a RenderFrameHost.
+  void CreateProxiesForSiteInstance(
+      FrameTreeNode* source,
+      SiteInstance* site_instance);
+
   // Clears process specific-state after a main frame process swap.
   // This destroys most of the frame tree but retains the root node so that
   // navigation state may be kept on it between process swaps. Used to
@@ -100,20 +108,19 @@ class CONTENT_EXPORT FrameTree {
   void SetFrameRemoveListener(
       const base::Callback<void(RenderFrameHost*)>& on_frame_removed);
 
-  // Creates a RenderViewHost for a new main frame RenderFrameHost in the given
+  // Creates a RenderViewHost for a new RenderFrameHost in the given
   // |site_instance|.  The RenderViewHost will have its Shutdown method called
   // when all of the RenderFrameHosts using it are deleted.
-  RenderViewHostImpl* CreateRenderViewHostForMainFrame(
-      SiteInstance* site_instance,
-      int routing_id,
-      int main_frame_routing_id,
-      bool swapped_out,
-      bool hidden);
-
-  // Returns the existing RenderViewHost for a new subframe RenderFrameHost.
+  RenderViewHostImpl* CreateRenderViewHost(SiteInstance* site_instance,
+                                           int routing_id,
+                                           int main_frame_routing_id,
+                                           bool swapped_out,
+                                           bool hidden);
+
+  // Returns the existing RenderViewHost for a new RenderFrameHost.
   // There should always be such a RenderViewHost, because the main frame
   // RenderFrameHost for each SiteInstance should be created before subframes.
-  RenderViewHostImpl* GetRenderViewHostForSubFrame(SiteInstance* site_instance);
+  RenderViewHostImpl* GetRenderViewHost(SiteInstance* site_instance);
 
   // Keeps track of which RenderFrameHosts are using each RenderViewHost.  When
   // the number drops to zero, we call Shutdown on the RenderViewHost.