Update from https://crrev.com/306655

cc/scheduler/scheduler_settings.cc

 // Copyright 2013 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/scheduler/scheduler_settings.h"
 
 #include "base/debug/trace_event_argument.h"
 #include "cc/trees/layer_tree_settings.h"
 
 namespace cc {
 
 SchedulerSettings::SchedulerSettings()
     : use_external_begin_frame_source(false),
       forward_begin_frames_to_children(false),
       main_frame_before_activation_enabled(false),
       impl_side_painting(false),
       timeout_and_draw_when_animation_checkerboards(true),
       maximum_number_of_failed_draws_before_draw_is_forced_(3),
       using_synchronous_renderer_compositor(false),
       throttle_frame_production(true),
       disable_hi_res_timer_tasks_on_battery(false),
+      main_thread_should_always_be_low_latency(false),
       background_frame_interval(base::TimeDelta::FromSeconds(1)) {
 }
 
 SchedulerSettings::SchedulerSettings(const LayerTreeSettings& settings)
     : use_external_begin_frame_source(settings.use_external_begin_frame_source),
       forward_begin_frames_to_children(
           settings.forward_begin_frames_to_children),
       main_frame_before_activation_enabled(
           settings.main_frame_before_activation_enabled),
       impl_side_painting(settings.impl_side_painting),
       timeout_and_draw_when_animation_checkerboards(
           settings.timeout_and_draw_when_animation_checkerboards),
       maximum_number_of_failed_draws_before_draw_is_forced_(
           settings.maximum_number_of_failed_draws_before_draw_is_forced_),
       using_synchronous_renderer_compositor(
           settings.using_synchronous_renderer_compositor),
       throttle_frame_production(settings.throttle_frame_production),
       disable_hi_res_timer_tasks_on_battery(
           settings.disable_hi_res_timer_tasks_on_battery),
+      main_thread_should_always_be_low_latency(
+          settings.main_thread_should_always_be_low_latency),
       background_frame_interval(base::TimeDelta::FromSecondsD(
           1.0 / settings.background_animation_rate)) {
 }
 
 SchedulerSettings::~SchedulerSettings() {}
 
 scoped_refptr<base::debug::ConvertableToTraceFormat>
 SchedulerSettings::AsValue() const {
   scoped_refptr<base::debug::TracedValue> state =
       new base::debug::TracedValue();
   state->SetBoolean("use_external_begin_frame_source",
                     use_external_begin_frame_source);
   state->SetBoolean("forward_begin_frames_to_children",
                     forward_begin_frames_to_children);
   state->SetBoolean("main_frame_before_activation_enabled",
                     main_frame_before_activation_enabled);
   state->SetBoolean("impl_side_painting", impl_side_painting);
   state->SetBoolean("timeout_and_draw_when_animation_checkerboards",
                     timeout_and_draw_when_animation_checkerboards);
   state->SetInteger("maximum_number_of_failed_draws_before_draw_is_forced_",
                     maximum_number_of_failed_draws_before_draw_is_forced_);
   state->SetBoolean("using_synchronous_renderer_compositor",
                     using_synchronous_renderer_compositor);
   state->SetBoolean("throttle_frame_production", throttle_frame_production);
   state->SetBoolean("disable_hi_res_timer_tasks_on_battery",
                     disable_hi_res_timer_tasks_on_battery);
+  state->SetBoolean("main_thread_should_always_be_low_latency",
+                    main_thread_should_always_be_low_latency);
   state->SetInteger("background_frame_interval",
                     background_frame_interval.InMicroseconds());
   return state;
 }
 
 }  // namespace cc