cc: Allow sending BeginMainFrame before draw or activation

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 b35cb7e6af619e5463650d4db93dd44924104278..52c9d56d2311bd1143e87c8b1b151e0bb6cecf0e 100644
--- a/cc/scheduler/scheduler_settings.h
+++ b/cc/scheduler/scheduler_settings.h
@@ -15,6 +15,8 @@ class CC_EXPORT SchedulerSettings {
   ~SchedulerSettings();
 
   bool deadline_scheduling_enabled;
+  bool start_commit_before_draw_enabled;
+  bool start_commit_before_activate_enabled;
   bool impl_side_painting;
   bool timeout_and_draw_when_animation_checkerboards;
   int maximum_number_of_failed_draws_before_draw_is_forced_;