cc: Refactor how picture layers are exposed to the tile manager.

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 95f702fb549f2b8a6c518737eb360dfa64c978e1..6dad2a2dba64d8b0078155e22e9ff35b84cf61cc 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -42,6 +42,7 @@ class LayerTreeSettings;
 class MemoryHistory;
 class OutputSurface;
 class PaintTimeCounter;
+class PictureLayerImpl;
 class Proxy;
 class ResourceProvider;
 class TileManager;
@@ -259,6 +260,9 @@ class CC_EXPORT LayerTreeImpl {
   LayerImpl* FindLayerThatIsHitByPointInTouchHandlerRegion(
       const gfx::PointF& screen_space_point);
 
+  void RegisterPictureLayerImpl(PictureLayerImpl* layer);
+  void UnregisterPictureLayerImpl(PictureLayerImpl* layer);
+
  protected:
   explicit LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl);
   void ReleaseResourcesRecursive(LayerImpl* current);