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

cc/resources/prioritized_tile.h

+// Copyright 2015 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_PRIORITIZED_TILE_H_
+#define CC_RESOURCES_PRIORITIZED_TILE_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/resources/tile.h"
+#include "cc/resources/tile_priority.h"
+
+namespace cc {
+class PictureLayerTiling;
+
+class CC_EXPORT PrioritizedTile {
+ public:
+  // This class is constructed and returned by a |PictureLayerTiling|, and
+  // represents a tile and its priority.
+  PrioritizedTile();
+  ~PrioritizedTile();
+
+  Tile* tile() const { return tile_; }
+  const TilePriority& priority() const { return priority_; }
+  bool is_occluded() const { return is_occluded_; }
+
+ private:
+  friend class PictureLayerTiling;
+
+  PrioritizedTile(Tile* tile, const TilePriority priority, bool is_occluded);
+
+  Tile* tile_;
+  TilePriority priority_;
+  bool is_occluded_;
+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_PRIORITIZED_TILE_H_