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

cc/resources/picture_layer_tiling.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_RESOURCES_PICTURE_LAYER_TILING_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 118 matching lines @@
       WhichTree tree,
       gfx::Size device_viewport,
       const gfx::RectF& viewport_in_layer_space,
       const gfx::RectF& visible_layer_rect,
       gfx::Size last_layer_bounds,
       gfx::Size current_layer_bounds,
       float last_layer_contents_scale,
       float current_layer_contents_scale,
       const gfx::Transform& last_screen_transform,
       const gfx::Transform& current_screen_transform,
-      int current_source_frame_number,
-      double current_frame_time,
+      double current_frame_time_in_seconds,
       bool store_screen_space_quads_on_tiles,
       size_t max_tiles_for_interest_area);
 
   // Copies the src_tree priority into the dst_tree priority for all tiles.
   // The src_tree priority is reset to the lowest priority possible.  This
   // also updates the pile on each tile to be the current client's pile.
   void DidBecomeActive();
 
+  bool NeedsUpdateForFrameAtTime(double frame_time_in_seconds) {
+    return frame_time_in_seconds != last_impl_frame_time_in_seconds_;
+  }
+
   scoped_ptr<base::Value> AsValue() const;
 
   static gfx::Rect ExpandRectEquallyToAreaBoundedBy(
       gfx::Rect starting_rect,
       int64 target_area,
       gfx::Rect bounding_rect);
 
  protected:
   typedef std::pair<int, int> TileMapKey;
   typedef base::hash_map<TileMapKey, scoped_refptr<Tile> > TileMap;
@@ skipping 10 matching lines @@
   gfx::Size layer_bounds_;
   TileResolution resolution_;
   PictureLayerTilingClient* client_;
 
   // Internal data.
   TilingData tiling_data_;
   TileMap tiles_;  // It is not legal to have a NULL tile in the tiles_ map.
   gfx::Rect live_tiles_rect_;
 
   // State saved for computing velocities based upon finite differences.
-  int last_source_frame_number_;
-  double last_impl_frame_time_;
+  double last_impl_frame_time_in_seconds_;
 
   friend class CoverageIterator;
 
  private:
   DISALLOW_ASSIGN(PictureLayerTiling);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_H_