Add LayerTreeHostSettings for synchronous compositor

cc/trees/layer_tree_settings.cc

 // 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.
 
 #include "cc/trees/layer_tree_settings.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 
 namespace cc {
 
 LayerTreeSettings::LayerTreeSettings()
     : accelerate_painting(false),
       compositor_frame_message(false),
       impl_side_painting(false),
       render_vsync_enabled(true),
       render_vsync_notification_enabled(false),
+      synchronously_disable_vsync(false),
       per_tile_painting_enabled(false),
       partial_swap_enabled(false),
       cache_render_pass_contents(true),
       right_aligned_scheduling_enabled(false),
       accelerated_animation_enabled(true),
       background_color_instead_of_checkerboard(false),
       show_overdraw_in_tracing(false),
       can_use_lcd_text(true),
       should_clear_root_render_pass(true),
       use_linear_fade_scrollbar_animator(false),
@@ skipping 23 matching lines @@
       highp_threshold_min(0),
       strict_layer_property_change_checking(false) {
   // TODO(danakj): Renable surface caching when we can do it more realiably.
   // crbug.com/170713
   cache_render_pass_contents = false;
 }
 
 LayerTreeSettings::~LayerTreeSettings() {}
 
 }  // namespace cc