cc: Add flag to disable future mask tiling.

cc/trees/layer_tree_settings.h

 // Copyright 2011 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_TREES_LAYER_TREE_SETTINGS_H_
 #define CC_TREES_LAYER_TREE_SETTINGS_H_
 
 #include <stddef.h>
 
 #include <vector>
@@ skipping 77 matching lines @@
   size_t gpu_decoded_image_budget_bytes = 96 * 1024 * 1024;
   size_t software_decoded_image_budget_bytes = 128 * 1024 * 1024;
   int max_preraster_distance_in_screen_pixels = 1000;
 
   bool enable_color_correct_rendering = false;
 
   // If set to true, this causes TileManager to verify that all required and NOW
   // tiles come before lower priority tiles.
   bool check_tile_priority_inversion = false;
 
+  // TODO(sunxd): remove this flag when filter demoting and aa of mask layers
+  // are implemented.
+  bool enable_mask_tiling = false;
+
   LayerTreeDebugState initial_debug_state;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_SETTINGS_H_