cc: GPU rasterize tiles synchronously in PrepareToDraw.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 03ddaa050d8288544f7fd87a59f981c484282061..ea73fbcaaa2982af1b55588870ad0ba233cc8217 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -53,6 +53,7 @@ class PaintTimeCounter;
 class PictureLayerImpl;
 class RasterTilePriorityQueue;
 class TileTaskWorkerPool;
+class Rasterizer;
 class RenderPassDrawQuad;
 class RenderingStatsInstrumentation;
 class ResourcePool;
@@ -500,6 +501,7 @@ class CC_EXPORT LayerTreeHostImpl
   // Only valid for synchronous (non-scheduled) single-threaded case.
   void SynchronouslyInitializeAllTiles();
 
+  virtual void CreateRasterizer(scoped_ptr<Rasterizer>* rasterizer);
   virtual void CreateResourceAndTileTaskWorkerPool(
       scoped_ptr<TileTaskWorkerPool>* tile_task_worker_pool,
       scoped_ptr<ResourcePool>* resource_pool,
@@ -612,6 +614,7 @@ class CC_EXPORT LayerTreeHostImpl
   bool use_gpu_rasterization_;
   GpuRasterizationStatus gpu_rasterization_status_;
   scoped_ptr<TileTaskWorkerPool> tile_task_worker_pool_;
+  scoped_ptr<Rasterizer> rasterizer_;
   scoped_ptr<ResourcePool> resource_pool_;
   scoped_ptr<ResourcePool> staging_resource_pool_;
   scoped_ptr<Renderer> renderer_;