HACK: Rasterize tiles immediately if there are only a few of them

cc/tile_manager.h

Index: cc/tile_manager.h
diff --git a/cc/tile_manager.h b/cc/tile_manager.h
index 6137aabec53371ce798052ea87e40dcf5ee32a3f..5ad3dd6b15f266fc307ff4d5a9874d6660ac047e 100644
--- a/cc/tile_manager.h
+++ b/cc/tile_manager.h
@@ -132,11 +132,12 @@ class CC_EXPORT TileManager {
   void OnImageDecodeTaskCompleted(
       scoped_refptr<Tile> tile, uint32_t pixel_ref_id);
   bool CanDispatchRasterTask(Tile* tile);
-  void DispatchOneRasterTask(scoped_refptr<Tile> tile);
+  void DispatchOneRasterTask(scoped_refptr<Tile> tile, bool immediate);
   void OnRasterTaskCompleted(
       scoped_refptr<Tile> tile,
       scoped_ptr<ResourcePool::Resource> resource,
-      int manage_tiles_call_count_when_dispatched);
+      int manage_tiles_call_count_when_dispatched,
+      bool dispatch_more);
   void DidFinishTileInitialization(Tile* tile);
   void DidTileRasterStateChange(Tile* tile, TileRasterState state);
   void DidTileBinChange(Tile* tile,