Moving deadline adjustment from SyntheticBeginFrameSource into BeginFrameArgs.

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index cc6ae1a39dc79c0e6a8f9dcb6b0fcc0b901ce589..126bebf93b08dbf15a6fdacfe13e8e2f17f4b0f5 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -64,8 +64,7 @@ void Scheduler::SyntheticBeginFrameSource::OnTimerTick() {
 BeginFrameArgs
 Scheduler::SyntheticBeginFrameSource::CreateSyntheticBeginFrameArgs(
     base::TimeTicks frame_time) {
-  base::TimeTicks deadline =
-      time_source_->NextTickTime() - scheduler_->EstimatedParentDrawTime();
+  base::TimeTicks deadline = time_source_->NextTickTime();
   return BeginFrameArgs::Create(
       frame_time, deadline, scheduler_->VSyncInterval());
 }
@@ -398,6 +397,9 @@ void Scheduler::BeginFrame(const BeginFrameArgs& args) {
   TRACE_EVENT1("cc", "Scheduler::BeginFrame", "args", ToTrace(args));
   DCHECK(settings_.throttle_frame_production);
 
+  BeginFrameArgs adjusted_args(args);
+  adjusted_args.deadline -= EstimatedParentDrawTime();

[brianderson, 2014/06/10 18:24:23]

I had some reservations about putting the adjustment inside of the
SyntheticBeginFrameSource as well, but I think it still makes the most sense
because, when we are using a real BeginFrame message, the sender is supposed to
adjust the deadline based on it's own expected draw time.

I agree that it's a bit confusing to apply the EstimatedParentDrawTime in some
cases but not others. I wonder if we can clarify the usage and reasoning with
better naming or if we need to explain things better with comments.

+
   bool should_defer_begin_frame;
   if (settings_.using_synchronous_renderer_compositor) {
     should_defer_begin_frame = false;
@@ -410,13 +412,13 @@ void Scheduler::BeginFrame(const BeginFrameArgs& args) {
   }
 
   if (should_defer_begin_frame) {
-    begin_retro_frame_args_.push_back(args);
+    begin_retro_frame_args_.push_back(adjusted_args);
     TRACE_EVENT_INSTANT0(
         "cc", "Scheduler::BeginFrame deferred", TRACE_EVENT_SCOPE_THREAD);
     return;
   }
 
-  BeginImplFrame(args);
+  BeginImplFrame(adjusted_args);
 }
 
 // BeginRetroFrame is called for BeginFrames that we've deferred because