Add VideoTrackSink interface to content/public

content/renderer/media/media_stream_video_track.cc

+// Copyright 2013 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/media/media_stream_video_track.h"
+
+#include "content/renderer/media/webrtc_video_sink_adapter.h"
+
+namespace content {
+
+// Wrapper which allows to use std::find_if() when adding and removing
+// sinks to/from |sinks_|.
+struct SinkWrapper {
+  explicit SinkWrapper(MediaStreamVideoSink* sink) : sink_(sink) {}
+  bool operator()(
+      const WebRtcVideoSinkAdapter* owner) {

[tommi (sloooow) - chröme, 2013/11/27 16:53:07]

is wrapping necessary? (I mean, I know the class name is SinkWrapper but...)

[perkj_chrome, 2013/11/28 13:32:45]

What do you mean? xians suggested this trick in order to be able to compare
MediaStreamVideoSink* with WebRtcVideoSinkAdapter*.

[tommi (sloooow) - chröme, 2013/11/28 14:32:21]

Sorry, unfortunate mix up of wrapping vs wrapping :)
I mean:

bool operator()(const WebRtcVideoSinkAdapter* owner) {

and not

bool operator()(
    const WebRtcVideoSinkAdapter* owner) {

:-)

+    return owner->sink() == sink_;
+  }
+  MediaStreamVideoSink* sink_;
+};
+
+MediaStreamVideoTrack::MediaStreamVideoTrack(webrtc::VideoTrackInterface* track)
+    : MediaStreamTrackExtraData(track),
+      video_track_(track) {
+}
+
+MediaStreamVideoTrack::~MediaStreamVideoTrack() {
+  DCHECK(sinks_.empty());
+}
+
+void MediaStreamVideoTrack::AddSink(MediaStreamVideoSink* sink) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(std::find_if(sinks_.begin(), sinks_.end(),
+                      SinkWrapper(sink)) == sinks_.end());
+  sinks_.push_back(new WebRtcVideoSinkAdapter(video_track_, sink));
+}
+
+void MediaStreamVideoTrack::RemoveSink(MediaStreamVideoSink* sink) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  ScopedVector<WebRtcVideoSinkAdapter>::iterator it =
+      std::find_if(sinks_.begin(), sinks_.end(), SinkWrapper(sink));
+  if (it == sinks_.end()) {
+    NOTREACHED();

[tommi (sloooow) - chröme, 2013/11/27 16:53:07]

NOTREACHED is considered dead code and works out to be a DCHECK.
Is the intention here to do:
DCHECK_NE(it, sinks_.end());
?

If so, then the if() shouldn't be necessary since this isn't a
supported/expected scenario.
If not, then NOTREACHED doesn't feel like the right thing to do since we will
certainly reach this code and maybe we should log an error instead.
WDYT?

[perkj_chrome, 2013/11/28 13:32:45]

Done.DCHECK_NE doesn't compile though. 

+    return;
+  }
+  sinks_.erase(it);
+}
+
+}  // namespace content