cc: Remove retro frames from scheduler.

content/renderer/gpu/compositor_external_begin_frame_source.cc

Index: content/renderer/gpu/compositor_external_begin_frame_source.cc
diff --git a/content/renderer/gpu/compositor_external_begin_frame_source.cc b/content/renderer/gpu/compositor_external_begin_frame_source.cc
index aa4a456ac29a56b6e5ce773be7bd196df9e59812..32da19acf6fcd155aa2e127bdf25ed48b2ef856b 100644
--- a/content/renderer/gpu/compositor_external_begin_frame_source.cc
+++ b/content/renderer/gpu/compositor_external_begin_frame_source.cc
@@ -40,6 +40,20 @@ void CompositorExternalBeginFrameSource::OnNeedsBeginFramesChanged(
   Send(new ViewHostMsg_SetNeedsBeginFrames(routing_id_, needs_begin_frames));
 }
 
+void CompositorExternalBeginFrameSource::DidFinishFrame(
+    cc::BeginFrameObserver* obs) {
+  DCHECK(CalledOnValidThread());
+  SetClientReady();

[enne (OOO), 2016/04/14 23:02:26]

Why do you need to call this? This should have already happened as soon as there
was an observer, I think?

+  // Send a MISSED begin frame if necessary.

[enne (OOO), 2016/04/14 23:02:26]

This looks like a pretty common pattern.  Is there some clean way to not repeat
this?

+  if (missed_begin_frame_args_.IsValid()) {
+    cc::BeginFrameArgs last_args = obs->LastUsedBeginFrameArgs();
+    if (!last_args.IsValid() ||
+        (missed_begin_frame_args_.frame_time > last_args.frame_time)) {
+      obs->OnBeginFrame(missed_begin_frame_args_);
+    }
+  }
+}
+
 void CompositorExternalBeginFrameSource::AddObserver(
     cc::BeginFrameObserver* obs) {
   DCHECK(CalledOnValidThread());