cc: Add flag to disable future mask tiling.

cc/trees/layer_tree_settings.cc

Index: cc/trees/layer_tree_settings.cc
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index 166d79c8ce7a95f7a560230fc225df6e8b083be4..1f7b9062d439dc790e344d6c21c64221995ca97d 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -77,6 +77,7 @@ bool LayerTreeSettings::operator==(const LayerTreeSettings& other) const {
              other.max_staging_buffer_usage_in_bytes &&
          gpu_memory_policy == other.gpu_memory_policy &&
          software_memory_policy == other.software_memory_policy &&
+         enable_mask_tiling == other.enable_mask_tiling &&
          LayerTreeDebugState::Equal(initial_debug_state,
                                     other.initial_debug_state);
 }