[DRAFT] Create RenderFrameHostManager.

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 4a1d841c0f3e842609cdf3d31673bd32d655966f..64b4ba94ad690d5eaaaa1d12cf03febf1579551d 100644
--- a/content/browser/frame_host/frame_tree.h
+++ b/content/browser/frame_host/frame_tree.h
@@ -33,9 +33,6 @@ class RenderWidgetHostDelegate;
 // TODO(ajwong): Move NavigationController ownership to the main frame
 // FrameTreeNode. Possibly expose access to it from here.
 //
-// TODO(ajwong): Currently this class only contains FrameTreeNodes for
-// subframes if the --site-per-process flag is enabled.
-//
 // This object is only used on the UI thread.
 class CONTENT_EXPORT FrameTree {
  public:
@@ -59,38 +56,15 @@ class CONTENT_EXPORT FrameTree {
   // if |on_node| is just doing a search over the tree.
   void ForEach(const base::Callback<bool(FrameTreeNode*)>& on_node) const;
 
-  // After the FrameTree is created, or after SwapMainFrame() has been called,
-  // the root node does not yet have a frame id. This is allocated by the
-  // renderer and is published to the browser process on the first navigation
-  // after a swap. These two functions are used to set the root node's frame
-  // id.
-  //
-  // TODO(ajwong): Remove these once RenderFrameHost's routing id replaces
-  // frame_id.
-  bool IsFirstNavigationAfterSwap() const;
-  void OnFirstNavigationAfterSwap(int main_frame_id);
-
   // Frame tree manipulation routines.
-  // TODO(creis): These should take in RenderFrameHost routing IDs.
-  void AddFrame(int render_frame_host_id,
-                int64 parent_frame_tree_node_id,
+  void AddFrame(RenderViewHostImpl* parent_render_view_host,
+                int render_frame_host_id,
+                int64 parent_frame_id,
                 int64 frame_id,
                 const std::string& frame_name);
-  void RemoveFrame(int64 parent_frame_id, int64 frame_id);
-  void SetFrameUrl(int64 frame_id, const GURL& url);
-
-  // Resets the FrameTree and changes RenderFrameHost for the main frame.
-  // 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
-  // support bookkeeping for top-level navigations.
-  //
-  // If |main_frame| is NULL, reset tree to initially constructed state.
-  //
-  // TODO(ajwong): This function should not be given a |main_frame|. This is
-  // required currently because the RenderViewHost owns its main frame. When
-  // that relation is fixed, the FrameTree should be responsible for
-  // created/destroying the main frame on the swap.
-  void SwapMainFrame(RenderFrameHostImpl* main_frame);
+  void RemoveFrame(int64 parent_frame_tree_node_id,
+                   int64 frame_tree_node_id);
+  void SetFrameUrl(int64 frame_tree_node_id, const GURL& url);
 
   // Convenience accessor for the main frame's RenderFrameHostImpl.
   RenderFrameHostImpl* GetMainFrame() const;
@@ -102,19 +76,25 @@ class CONTENT_EXPORT FrameTree {
   void SetFrameRemoveListener(
       const base::Callback<void(RenderViewHostImpl*, int64)>& on_frame_removed);
 
+  // Get the RenderViewHost needed for a new RenderFrameHost in the given
+  // |site_instance|.  Creates it if necessary and increments the refcount.
+  // The RenderViewHost will have its Shutdown method called when all of the
+  // RenderFrameHosts using it are deleted.
+  RenderViewHostImpl* GetRenderViewHostForNewFrame(SiteInstance* site_instance,
+                                                   int routing_id,
+                                                   int main_frame_routing_id,
+                                                   bool swapped_out,
+                                                   bool hidden);
+
   FrameTreeNode* root() const { return root_.get(); }
 
  private:
-  // Returns the FrameTreeNode with the given renderer-specific |frame_id|.
-  // For internal use only.
-  // TODO(creis): Replace this with a version that takes in a routing ID.
-  FrameTreeNode* FindByFrameID(int64 frame_id);
+  typedef base::hash_map<int, RenderViewHostImpl*> RenderViewHostMap;
 
   scoped_ptr<FrameTreeNode> CreateNode(int64 frame_id,
                                        const std::string& frame_name,
-                                       int render_frame_host_id,
                                        Navigator* navigator,
-                                       RenderProcessHost* render_process_host);
+                                       RenderViewHostImpl* render_view_host);
 
   // These delegates are installed into all the RenderViewHosts and
   // RenderFrameHosts that we create.
@@ -124,6 +104,11 @@ class CONTENT_EXPORT FrameTree {
 
   scoped_ptr<FrameTreeNode> root_;
 
+  // Map of SiteInstance ID to RenderViewHost, which we can consult when
+  // creating a new RenderFrameHost in this tree.  RenderViewHosts are kept
+  // alive as long as they have at least one RenderFrameHost using them.
+  RenderViewHostMap render_view_host_map_;
+
   base::Callback<void(RenderViewHostImpl*, int64)> on_frame_removed_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameTree);