cc: Control defer_commits logic by Scheduler

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 dea25b40871b440405ed48ea51300224770c26cb..7f97aa016bd59189b721d6dc54fd55e6d5f41878 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -46,7 +46,8 @@ 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),
+      defer_commits_(false) {
 }
 
 const char* SchedulerStateMachine::OutputSurfaceStateToString(
@@ -236,6 +237,7 @@ scoped_ptr<base::Value> SchedulerStateMachine::AsValue() const  {
   minor_state->SetBoolean("skip_next_begin_main_frame_to_reduce_latency",
                           skip_next_begin_main_frame_to_reduce_latency_);
   minor_state->SetBoolean("continuous_painting", continuous_painting_);
+  minor_state->SetBoolean("defer_commits", defer_commits_);
   state->Set("minor_state", minor_state.release());
 
   return state.PassAs<base::Value>();
@@ -438,6 +440,10 @@ bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
   if (!visible_)
     return false;
 
+  // We do not need commits if commits are deferred.
+  if (defer_commits_)
+    return false;
+
   // We want to start the first commit after we get a new output surface ASAP.
   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT)
     return true;
@@ -734,6 +740,10 @@ bool SchedulerStateMachine::SupportsProactiveBeginFrame() const {
   return !settings_.using_synchronous_renderer_compositor;
 }
 
+void SchedulerStateMachine::SetDeferCommits(bool defer_commits) {
+  defer_commits_ = defer_commits;
+}
+
 // 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 {
@@ -746,6 +756,10 @@ bool SchedulerStateMachine::BeginFrameNeededToAnimateOrDraw() const {
   if (!can_draw_)
     return false;
 
+  // New BeginFrame should not be triggered when we need to defer commits.
+  if (defer_commits_)
+    return false;
+
   // 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)
@@ -781,6 +795,10 @@ bool SchedulerStateMachine::ProactiveBeginFrameWanted() const {
   if (!visible_)
     return false;
 
+  // New BeginFrame should not be triggered when we need to defer commits.
+  if (defer_commits_)
+    return false;
+
   // We should proactively request a BeginImplFrame if a commit is pending
   // because we will want to draw if the commit completes quickly.
   if (needs_commit_ || commit_state_ != COMMIT_STATE_IDLE)