cc: Support on demand raster with ganesh

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 3d8a9a29e0daa4af6bc4bce46c6139c69c5404ce..1cc58182c0d4ce2ee180497e3593bc010815e80e 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -229,6 +229,7 @@ class CC_EXPORT LayerTreeHostImpl
 
   // RendererClient implementation.
   virtual void SetFullRootLayerDamage() OVERRIDE;
+  virtual void RunOnDemandRasterTask(Task* on_demand_raster_task) OVERRIDE;
 
   // TileManagerClient implementation.
   virtual const std::vector<PictureLayerImpl*>& GetPictureLayers() OVERRIDE;
@@ -573,6 +574,10 @@ class CC_EXPORT LayerTreeHostImpl
   scoped_ptr<ResourcePool> staging_resource_pool_;
   scoped_ptr<Renderer> renderer_;
 
+  scoped_ptr<TaskGraphRunner> synchronous_on_demand_task_graph_runner_;

[reveman, 2014/06/20 03:56:30]

you could just call it |synchronous_task_graph_runner_| if you like as there's
nothing that prevents it from being used for some other synchronous tasks in the
future.

+  TaskGraphRunner* on_demand_task_graph_runner_;
+  NamespaceToken on_demand_task_namespace_;
+
   GlobalStateThatImpactsTilePriority global_tile_state_;
 
   // Tree currently being drawn.