cc: Simplify the logic for deciding to update tile priorities.

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 41b6f65bad608a140b836455b9f97aead4df64da..cf47d681bca0b79c744d50a6696e2ab43f9c56ea 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -119,12 +119,6 @@ class CC_EXPORT LayerTreeImpl {
     has_transparent_background_ = transparent;
   }
 
-  enum UpdateDrawPropertiesReason {

[enne (OOO), 2013/04/22 17:03:48]

<3

-    UPDATE_PENDING_TREE,
-    UPDATE_ACTIVE_TREE,
-    UPDATE_ACTIVE_TREE_FOR_DRAW
-  };
-
   gfx::Transform ImplTransform() const;
 
   void SetPageScaleFactorAndLimits(float page_scale_factor,
@@ -142,8 +136,10 @@ class CC_EXPORT LayerTreeImpl {
   }
   float sent_page_scale_delta() const { return sent_page_scale_delta_; }
 
-  // Updates draw properties and render surface layer list
-  void UpdateDrawProperties(UpdateDrawPropertiesReason reason);
+  // Updates draw properties and render surface layer list, as well as tile
+  // priorities.
+  void UpdateDrawProperties();
+
   void set_needs_update_draw_properties() {
     needs_update_draw_properties_ = true;
   }
@@ -248,6 +244,8 @@ class CC_EXPORT LayerTreeImpl {
   // structural differences relative to the active tree.
   bool needs_full_tree_sync_;
 
+  base::TimeTicks frame_time_last_update_tile_priorities_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };