cc: Split RasterTilePriorityQueue into required and all based on type.

cc/resources/raster_tile_priority_queue_required.h

Index: cc/resources/raster_tile_priority_queue_required.h
diff --git a/cc/resources/raster_tile_priority_queue_required.h b/cc/resources/raster_tile_priority_queue_required.h
new file mode 100644
index 0000000000000000000000000000000000000000..6e762bcb694b1721673737f8c4302b4e10babb90
--- /dev/null
+++ b/cc/resources/raster_tile_priority_queue_required.h
@@ -0,0 +1,37 @@
+// 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_RASTER_TILE_PRIORITY_QUEUE_REQUIRED_H_
+#define CC_RESOURCES_RASTER_TILE_PRIORITY_QUEUE_REQUIRED_H_
+
+#include <vector>
+
+#include "cc/layers/picture_layer_impl.h"
+#include "cc/resources/raster_tile_priority_queue.h"
+#include "cc/resources/tiling_set_raster_queue.h"
+
+namespace cc {
+class Tile;
+
+class RasterTilePriorityQueueRequired : public RasterTilePriorityQueue {
+ public:
+  RasterTilePriorityQueueRequired();
+  ~RasterTilePriorityQueueRequired() override;
+
+  bool IsEmpty() const override;
+  Tile* Top() override;
+  void Pop() override;
+
+ private:
+  friend class RasterTilePriorityQueue;
+
+  void Build(const std::vector<PictureLayerImpl::Pair>& paired_layers,
+             Type type);
+
+  ScopedPtrVector<TilingSetRasterQueue> tiling_set_queues_;
+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_RASTER_TILE_PRIORITY_QUEUE_REQUIRED_H_