cc: Remove retro frames from scheduler.

content/renderer/gpu/compositor_external_begin_frame_source.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/gpu/compositor_external_begin_frame_source.h"
 
 #include "content/common/view_messages.h"
 #include "ipc/ipc_sync_channel.h"
 #include "ipc/ipc_sync_message_filter.h"
 
@@ skipping 22 matching lines @@
 }
 
 void CompositorExternalBeginFrameSource::OnNeedsBeginFramesChanged(
     bool needs_begin_frames) {
   DCHECK(CalledOnValidThread());
   if (!needs_begin_frames)
     missed_begin_frame_args_ = cc::BeginFrameArgs();
   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());
   SetClientReady();
   BeginFrameSourceBase::AddObserver(obs);
   // Send a MISSED begin frame if necessary.
   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)) {
@@ skipping 31 matching lines @@
   missed_begin_frame_args_ = args;
   missed_begin_frame_args_.type = cc::BeginFrameArgs::MISSED;
   CallOnBeginFrame(args);
 }
 
 bool CompositorExternalBeginFrameSource::Send(IPC::Message* message) {
   return message_sender_->Send(message);
 }
 
 }  // namespace content