cc: Separate the priority from the tile and put in new PrioritizedTile

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 edd139997ab9f377e54d758e2c8e95d7dfa1ee72..94d8290c8206c7a9ffd344ab06e6df49112b0b17 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -29,6 +29,7 @@ class TracedValue;
 namespace cc {
 
 class PictureLayerTiling;
+class PrioritizedTile;
 class RasterSource;
 
 class CC_EXPORT PictureLayerTilingClient {
@@ -113,10 +114,9 @@ class CC_EXPORT PictureLayerTiling {
       all_tiles.push_back(it->second.get());
     return all_tiles;
   }
-  void UpdateAllTilePrioritiesForTesting() {
-    for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
-      UpdateTilePriority(it->second.get());
-  }
+  std::map<const Tile*, PrioritizedTile>
+  UpdateAndGetAllPrioritizedTilesForTesting();
+
   std::vector<scoped_refptr<Tile>> AllRefTilesForTesting() const {
     std::vector<scoped_refptr<Tile>> all_tiles;
     for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
@@ -211,6 +211,7 @@ class CC_EXPORT PictureLayerTiling {
 
  protected:
   friend class CoverageIterator;
+  friend class PrioritizedTile;
   friend class TilingSetRasterQueueAll;
   friend class TilingSetRasterQueueRequired;
   friend class TilingSetEvictionQueue;
@@ -274,7 +275,7 @@ class CC_EXPORT PictureLayerTiling {
   bool IsTileOccludedOnCurrentTree(const Tile* tile) const;
   bool ShouldCreateTileAt(int i, int j) const;
   bool IsTileOccluded(const Tile* tile) const;
-  void UpdateTilePriority(Tile* tile) const;
+  void UpdateTilePriority(PrioritizedTile* prioritized_tile) const;
   TilePriority ComputePriorityForTile(const Tile* tile) const;
   bool has_visible_rect_tiles() const { return has_visible_rect_tiles_; }
   bool has_skewport_rect_tiles() const { return has_skewport_rect_tiles_; }