Make cricket::VideoCapturer implement VideoSourceInterface

webrtc/media/base/videosourceinterface.h

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_
+#define WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_
+
+#include "webrtc/media/base/videosinkinterface.h"
+#include "webrtc/base/callback.h"
+
+namespace rtc {
+
+struct VideoSinkHints {

[pthatcher1, 2016/02/08 20:59:40]

This could use a comment explaining what it is and how it needs to be
communicated between sink and source.

[perkj_webrtc, 2016/02/09 13:23:57]

Done.

+  bool operator==(const VideoSinkHints& rh) const {
+    return can_apply_rotation == rh.can_apply_rotation;
+  }
+  bool operator!=(const VideoSinkHints& rh) const { return !operator==(rh); }
+
+  // Tells the source whether the sink can handle rotation. By default, the
+  // rotation is applied by the source.
+  bool can_apply_rotation = false;
+};
+
+template <typename VideoFrameT>
+class VideoSourceInterface {
+ public:
+  virtual void AddSink(VideoSinkInterface<VideoFrameT>* sink) = 0;

[nisse-webrtc, 2016/02/08 14:57:04]

I don't quite understand the need for both AddSink and AddOrUpdateSink.

AddSink is equivalent to AddOrUpdateSink with default set of hints?

[pthatcher1, 2016/02/08 20:59:40]

Originally, I thought that would be annoying to the caller to have to figure out
the hints or create a default one.  But now that I think about it, it's probably
better to be explicit, and it would be nice to have only two methods: add/update
and remove.

[perkj_webrtc, 2016/02/09 13:23:57]

Done.

+  // RemoveSink must guarantee that at the time the method returns,
+  // there is no current and no future calls to VideoSinkInterface::OnFrame.
+  virtual void RemoveSink(VideoSinkInterface<VideoFrameT>* sink) = 0;
+  virtual void AddOrUpdateSink(VideoSinkInterface<VideoFrameT>* sink,
+                               const VideoSinkHints& hints) = 0;
+
+ protected:
+  virtual ~VideoSourceInterface() {}
+};
+
+}  // namespace rtc
+#endif  // WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_