cc: Make the TileManager operate on ManagedTileState directly

cc/picture_layer_tiling.h

Index: cc/picture_layer_tiling.h
diff --git a/cc/picture_layer_tiling.h b/cc/picture_layer_tiling.h
index bf504b8386ba13362a05668c8d45143f5feee3db..bd1c21af9b1cfc5a9fc547a16e5a192a4b941335 100644
--- a/cc/picture_layer_tiling.h
+++ b/cc/picture_layer_tiling.h
@@ -19,6 +19,7 @@
 namespace cc {
 
 class PictureLayerTiling;
+class ManagedTileState;
 
 class PictureLayerTilingClient {
  public:
@@ -33,6 +34,16 @@ class PictureLayerTilingClient {
     gfx::Size content_bounds) = 0;
 };
 
+class TileHandle {
+ public:
+  TileHandle(scoped_refptr<Tile> tile);
+  ~TileHandle();
+  Tile* tile() const { return tile_.get(); }
+ private:
+  scoped_refptr<Tile> tile_;
+  scoped_refptr<ManagedTileState> managed_tile_state_;
+};
+
 class CC_EXPORT PictureLayerTiling {
  public:
   ~PictureLayerTiling();
@@ -61,7 +72,7 @@ class CC_EXPORT PictureLayerTiling {
     std::vector<Tile*> all_tiles;
     for (TileMap::const_iterator it = tiles_.begin();
          it != tiles_.end(); ++it)
-      all_tiles.push_back(it->second);
+      all_tiles.push_back(it->second.tile());
     return all_tiles;
   }
 
@@ -148,7 +159,7 @@ class CC_EXPORT PictureLayerTiling {
 
  protected:
   typedef std::pair<int, int> TileMapKey;
-  typedef base::hash_map<TileMapKey, scoped_refptr<Tile> > TileMap;
+  typedef base::hash_map<TileMapKey, TileHandle> TileMap;
 
   PictureLayerTiling(float contents_scale);
   Tile* TileAt(int, int) const;