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"
@@ skipping 34 matching lines @@
       max_partial_texture_updates(std::numeric_limits<size_t>::max()),
       num_raster_threads(1),
       default_tile_size(gfx::Size(256, 256)),
       max_untiled_layer_size(gfx::Size(512, 512)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       use_pinch_zoom_scrollbars(false),
       // At 256x256 tiles, 128 tiles cover an area of 2048x4096 pixels.
       max_tiles_for_interest_area(128),
       max_unused_resource_memory_percentage(100),
       highp_threshold_min(0),
-      strict_layer_property_change_checking(false) {
+      strict_layer_property_change_checking(false),
+      enable_synchronous_compositing(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