Revert of cc: Remove tile sharing from tilings.

cc/resources/raster_tile_priority_queue_all.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_RASTER_TILE_PRIORITY_QUEUE_ALL_H_
 #define CC_RESOURCES_RASTER_TILE_PRIORITY_QUEUE_ALL_H_
 
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 13 matching lines @@
     PairedTilingSetQueue();
     PairedTilingSetQueue(const PictureLayerImpl::Pair& layer_pair,
                          TreePriority tree_priority);
     ~PairedTilingSetQueue();
 
     bool IsEmpty() const;
     Tile* Top(TreePriority tree_priority);
     void Pop(TreePriority tree_priority);
 
     WhichTree NextTileIteratorTree(TreePriority tree_priority) const;
+    void SkipTilesReturnedByTwin(TreePriority tree_priority);
 
     scoped_refptr<base::trace_event::ConvertableToTraceFormat> StateAsValue()
         const;
 
     const TilingSetRasterQueueAll* active_queue() const {
       return active_queue_.get();
     }
     const TilingSetRasterQueueAll* pending_queue() const {
       return pending_queue_.get();
     }
 
    private:
     scoped_ptr<TilingSetRasterQueueAll> active_queue_;
     scoped_ptr<TilingSetRasterQueueAll> pending_queue_;
+    bool has_both_layers_;
 
     // Set of returned tiles (excluding the current one) for DCHECKing.
     std::set<const Tile*> returned_tiles_for_debug_;
   };
 
   RasterTilePriorityQueueAll();
   ~RasterTilePriorityQueueAll() override;
 
   bool IsEmpty() const override;
   Tile* Top() override;
@@ skipping 10 matching lines @@
   // objects directly (ie std::vector<PairedTilingSetQueue>.
   ScopedPtrVector<PairedTilingSetQueue> paired_queues_;
   TreePriority tree_priority_;
 
   DISALLOW_COPY_AND_ASSIGN(RasterTilePriorityQueueAll);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_RASTER_TILE_PRIORITY_QUEUE_ALL_H_