Move direct use of VideoCapturer::VideoAdapter to VideoSinkWants.

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"
+#include "webrtc/base/optional.h"
 
 namespace rtc {
 
 // VideoSinkWants is used for notifying the source of properties a video frame
 // should have when it is delivered to a certain sink.
 struct VideoSinkWants {
   bool operator==(const VideoSinkWants& rh) const {
     return rotation_applied == rh.rotation_applied;
   }
   bool operator!=(const VideoSinkWants& rh) const { return !operator==(rh); }
 
   // Tells the source whether the sink wants frames with rotation applied.
   // By default, the rotation is applied by the source.
   bool rotation_applied = true;
+
+  // Tells the source the maximum number of pixels the sink wants.
+  rtc::Optional<int> max_pixel_count;
+  // The sink can consume this amount of pixels but wants more. The source
+  // should produce a resolution one "step" higher than this.

[pthatcher1, 2016/02/25 07:40:30]

Can we add a little to this?  Perhaps like so: "Like max_pixel_count, but
relative to the given value.  The max should be one "step up" from the given
value.  In practice, this means the sink can consume this amount of pixels but
wants more and the should produce a resolution one "step" higher than this, but
not higher".

[perkj_webrtc, 2016/02/25 13:57:07]

Done.

+  rtc::Optional<int> max_pixel_count_step_up;
 };
 
 template <typename VideoFrameT>
 class VideoSourceInterface {
  public:
   virtual void AddOrUpdateSink(VideoSinkInterface<VideoFrameT>* sink,
                                const VideoSinkWants& wants) = 0;
   // 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;
 
  protected:
   virtual ~VideoSourceInterface() {}
 };
 
 }  // namespace rtc
 #endif  // WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_