cc: Split RasterTilePriorityQueue into required and all based on type.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 98d7e4b0e004c9c4aa913a33d8cba0c6a9d43f48..8b431c4db079c402afaab271e230f429a324e525 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -242,9 +242,9 @@ class CC_EXPORT LayerTreeHostImpl
   void NotifyReadyToActivate() override;
   void NotifyReadyToDraw() override;
   void NotifyTileStateChanged(const Tile* tile) override;
-  void BuildRasterQueue(RasterTilePriorityQueue* queue,
-                        TreePriority tree_priority,
-                        RasterTilePriorityQueue::Type type) override;
+  scoped_ptr<RasterTilePriorityQueue> BuildRasterQueue(
+      TreePriority tree_priority,
+      RasterTilePriorityQueue::Type type) override;
   void BuildEvictionQueue(EvictionTilePriorityQueue* queue,
                           TreePriority tree_priority) override;