Unified BeginFrame scheduling

cc/scheduler/scheduler_state_machine.cc

Index: cc/scheduler/scheduler_state_machine.cc
diff --git a/cc/scheduler/scheduler_state_machine.cc b/cc/scheduler/scheduler_state_machine.cc
index 723c40c80c276d42ce3d1e2df2c58f51dfad5742..33ae41b3bd4405c077ba43abd317b96c2b33e1f2 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -47,7 +47,8 @@ SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
       smoothness_takes_priority_(false),
       skip_next_begin_main_frame_to_reduce_latency_(false),
       skip_begin_main_frame_to_reduce_latency_(false),
-      continuous_painting_(false) {
+      continuous_painting_(false),
+      children_need_begin_frames_(false) {
 }
 
 const char* SchedulerStateMachine::OutputSurfaceStateToString(
@@ -733,6 +734,12 @@ bool SchedulerStateMachine::SupportsProactiveBeginFrame() const {
   return !settings_.using_synchronous_renderer_compositor;
 }
 
+void SchedulerStateMachine::SetChildrenNeedBeginFrames(
+    bool children_need_begin_frames) {
+  DCHECK(settings_.begin_frame_publisher);
+  children_need_begin_frames_ = children_need_begin_frames;
+}
+
 // These are the cases where we definitely (or almost definitely) have a
 // new frame to animate and/or draw and can draw.
 bool SchedulerStateMachine::BeginFrameNeededToAnimateOrDraw() const {
@@ -745,6 +752,9 @@ bool SchedulerStateMachine::BeginFrameNeededToAnimateOrDraw() const {
   if (!can_draw_)
     return false;
 
+  if (children_need_begin_frames_)
+    return true;
+
   // The forced draw respects our normal draw scheduling, so we need to
   // request a BeginImplFrame for it.
   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)