Update from https://crrev.com/306655

cc/scheduler/scheduler_settings.h

Index: cc/scheduler/scheduler_settings.h
diff --git a/cc/scheduler/scheduler_settings.h b/cc/scheduler/scheduler_settings.h
index e3fd4255aa30e42cf6edb5092ee21c8c912e71a9..4ff3c7eb5f7a3bcce279d38dd28d6b91e8dc4716 100644
--- a/cc/scheduler/scheduler_settings.h
+++ b/cc/scheduler/scheduler_settings.h
@@ -35,6 +35,12 @@ class CC_EXPORT SchedulerSettings {
   bool throttle_frame_production;
   bool disable_hi_res_timer_tasks_on_battery;
 
+  // In main thread low latency mode the entire
+  // BeginMainFrame->Commit->Activation->Draw cycle should complete before
+  // starting the next cycle.  Additionally, BeginMainFrame and Commit are
+  // completed atomically with no other tasks or actions occuring between them.
+  bool main_thread_should_always_be_low_latency;
+
   base::TimeDelta background_frame_interval;
 
   scoped_refptr<base::debug::ConvertableToTraceFormat> AsValue() const;