Keep vsync enabled while there is a pending requestAnimationFrame

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 c55631d9122ce770f667bd809b153e5660909447..3af3c41a476b958149fbcfe00ea8a40418137210 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -32,6 +32,7 @@ SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
       can_draw_(false),
       has_pending_tree_(false),
       draw_if_possible_failed_(false),
+      animate_requested_(false),
       texture_state_(LAYER_TEXTURE_STATE_UNLOCKED),
       output_surface_state_(OUTPUT_SURFACE_ACTIVE) {}
 
@@ -264,6 +265,7 @@ void SchedulerStateMachine::UpdateState(Action action) {
       commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
       needs_commit_ = false;
       needs_forced_commit_ = false;
+      animate_requested_ = false;
       return;
 
     case ACTION_COMMIT:
@@ -331,6 +333,9 @@ bool SchedulerStateMachine::VSyncCallbackNeeded() const {
   if (has_pending_tree_)
     return true;
 
+  if (animate_requested_)
+    return true;
+
   // If we can't draw, don't tick until we are notified that we can draw again.
   if (!can_draw_)
     return false;
@@ -385,6 +390,10 @@ void SchedulerStateMachine::DidDrawIfPossibleCompleted(bool success) {
 
 void SchedulerStateMachine::SetNeedsCommit() { needs_commit_ = true; }
 
+void SchedulerStateMachine::SetAnimateRequested() {
+  animate_requested_ = true;
+}
+
 void SchedulerStateMachine::SetNeedsForcedCommit() {
   needs_forced_commit_ = true;
   expect_immediate_begin_frame_ = true;