cc: Move --num-raster-threads setting to LayerTreeSettings.

cc/tile_manager.h

Index: cc/tile_manager.h
diff --git a/cc/tile_manager.h b/cc/tile_manager.h
index 2d57f7d04312d5607630b68a75f7b5845c921e5b..9e3ff436733996341bd88d4fa59d0b9f46df10ec 100644
--- a/cc/tile_manager.h
+++ b/cc/tile_manager.h
@@ -68,7 +68,9 @@ class CC_EXPORT ManagedTileState {
 // created, and unregister from the manager when they are deleted.
 class CC_EXPORT TileManager {
  public:
-  TileManager(TileManagerClient* client, ResourceProvider *resource_provider);
+  TileManager(TileManagerClient* client,
+              ResourceProvider *resource_provider,
+              size_t num_raster_threads);
   virtual ~TileManager();
 
   const GlobalStateThatImpactsTilePriority& GlobalState() const { return global_state_; }
@@ -102,6 +104,7 @@ class CC_EXPORT TileManager {
   scoped_ptr<ResourcePool> resource_pool_;
   bool manage_tiles_pending_;
   int pending_raster_tasks_;
+  size_t num_raster_threads_;
   scoped_refptr<base::SequencedWorkerPool> worker_pool_;
 
   GlobalStateThatImpactsTilePriority global_state_;