cc: Change TileManager iterators to be queues.

cc/layers/picture_layer_impl.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_LAYERS_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <string>
 #include <vector>
 
 #include "cc/base/cc_export.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/resources/picture_layer_tiling.h"
 #include "cc/resources/picture_layer_tiling_set.h"
 #include "cc/resources/picture_pile_impl.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkPicture.h"
 
 namespace cc {
 
 struct AppendQuadsData;
 class MicroBenchmarkImpl;
 class Tile;
 
 class CC_EXPORT PictureLayerImpl
     : public LayerImpl,
       NON_EXPORTED_BASE(public PictureLayerTilingClient) {
  public:
+  struct CC_EXPORT Pair {
+    Pair();
+    Pair(PictureLayerImpl* active_layer, PictureLayerImpl* pending_layer);
+    ~Pair();
+
+    PictureLayerImpl* active;
+    PictureLayerImpl* pending;
+  };
+
   class CC_EXPORT LayerRasterTileIterator {
    public:
     LayerRasterTileIterator();
     LayerRasterTileIterator(PictureLayerImpl* layer, bool prioritize_low_res);
     ~LayerRasterTileIterator();
 
     Tile* operator*();
     LayerRasterTileIterator& operator++();
     operator bool() const;
 
@@ skipping 166 matching lines @@
   gfx::Size viewport_size_for_tile_priority_;
   gfx::Transform screen_space_transform_for_tile_priority_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_