Chromium -> Mojo roll.

cc/resources/picture_layer_tiling.h

Index: cc/resources/picture_layer_tiling.h
diff --git a/cc/resources/picture_layer_tiling.h b/cc/resources/picture_layer_tiling.h
index 65e7ee0e3f90250c0194a0e6ce5f45aaaddfdab8..ea258a3084fe3df5afab1c696d6278cab769a773 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -5,7 +5,7 @@
 #ifndef CC_RESOURCES_PICTURE_LAYER_TILING_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_H_
 
-#include <set>
+#include <map>
 #include <utility>
 #include <vector>
 
@@ -140,6 +140,8 @@ class CC_EXPORT PictureLayerTiling {
   bool IsTileRequiredForDrawIfVisible(const Tile* tile) const;
 
   void UpdateTileAndTwinPriority(Tile* tile) const;
+  TilePriority ComputePriorityForTile(const Tile* tile) const;
+  void UpdateRequiredStateForTile(Tile* tile, WhichTree tree) const;
   bool has_visible_rect_tiles() const { return has_visible_rect_tiles_; }
   bool has_skewport_rect_tiles() const { return has_skewport_rect_tiles_; }
   bool has_soon_border_rect_tiles() const {
@@ -211,7 +213,8 @@ class CC_EXPORT PictureLayerTiling {
                                 double current_frame_time_in_seconds,
                                 const Occlusion& occlusion_in_layer_space);
 
-  void GetAllTilesForTracing(std::set<const Tile*>* tiles) const;
+  void GetAllTilesAndPrioritiesForTracing(
+      std::map<const Tile*, TilePriority>* tile_map) const;
   void AsValueInto(base::trace_event::TracedValue* array) const;
   size_t GPUMemoryUsageInBytes() const;
 
@@ -232,7 +235,7 @@ class CC_EXPORT PictureLayerTiling {
       RectExpansionCache* cache);
 
   bool has_ever_been_updated() const {
-    return last_impl_frame_time_in_seconds_ != 0.0;
+    return visible_rect_history_[0].frame_time_in_seconds != 0.0;
   }
 
  protected:
@@ -244,6 +247,11 @@ class CC_EXPORT PictureLayerTiling {
   typedef std::pair<int, int> TileMapKey;
   typedef base::hash_map<TileMapKey, scoped_refptr<Tile>> TileMap;
 
+  struct FrameVisibleRect {
+    gfx::Rect visible_rect_in_content_space;
+    double frame_time_in_seconds = 0.0;
+  };
+
   PictureLayerTiling(float contents_scale,
                      scoped_refptr<RasterSource> raster_source,
                      PictureLayerTilingClient* client,
@@ -279,9 +287,21 @@ class CC_EXPORT PictureLayerTiling {
   bool NeedsUpdateForFrameAtTimeAndViewport(
       double frame_time_in_seconds,
       const gfx::Rect& viewport_in_layer_space) {
-    return frame_time_in_seconds != last_impl_frame_time_in_seconds_ ||
+    return frame_time_in_seconds !=
+               visible_rect_history_[0].frame_time_in_seconds ||
            viewport_in_layer_space != last_viewport_in_layer_space_;
   }
+  void UpdateVisibleRectHistory(
+      double frame_time_in_seconds,
+      const gfx::Rect& visible_rect_in_content_space) {
+    visible_rect_history_[1] = visible_rect_history_[0];
+    visible_rect_history_[0].frame_time_in_seconds = frame_time_in_seconds;
+    visible_rect_history_[0].visible_rect_in_content_space =
+        visible_rect_in_content_space;
+    // If we don't have a second history item, set it to the most recent one.
+    if (visible_rect_history_[1].frame_time_in_seconds == 0.0)
+      visible_rect_history_[1] = visible_rect_history_[0];
+  }
 
   const size_t max_tiles_for_interest_area_;
   const float skewport_target_time_in_seconds_;
@@ -298,10 +318,9 @@ class CC_EXPORT PictureLayerTiling {
   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.
-  double last_impl_frame_time_in_seconds_;
   gfx::Rect last_viewport_in_layer_space_;
-  gfx::Rect last_visible_rect_in_content_space_;
+  // State saved for computing velocities based upon finite differences.
+  FrameVisibleRect visible_rect_history_[2];
 
   bool can_require_tiles_for_activation_;