Delete empty API files and cleaned up includes.

webrtc/api/videosourceproxy.h

 /*
  *  Copyright 2012 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_API_VIDEOSOURCEPROXY_H_
 #define WEBRTC_API_VIDEOSOURCEPROXY_H_
 
 #include "webrtc/api/proxy.h"
-#include "webrtc/api/videosourceinterface.h"
+#include "webrtc/api/mediastreaminterface.h"
 
 namespace webrtc {
 
 // VideoTrackSourceInterface makes sure the real VideoTrackSourceInterface
 // implementation is
 // destroyed on the signaling thread and marshals all method calls to the
 // signaling thread.
 BEGIN_PROXY_MAP(VideoTrackSource)
 PROXY_CONSTMETHOD0(SourceState, state)
 PROXY_CONSTMETHOD0(bool, remote)
 PROXY_METHOD0(cricket::VideoCapturer*, GetVideoCapturer)
 PROXY_METHOD0(void, Stop)
 PROXY_METHOD0(void, Restart)
 PROXY_CONSTMETHOD0(bool, is_screencast)
 PROXY_CONSTMETHOD0(bool, needs_denoising)
 PROXY_METHOD2(void,
               AddOrUpdateSink,
               rtc::VideoSinkInterface<cricket::VideoFrame>*,
               const rtc::VideoSinkWants&)
 PROXY_METHOD1(void, RemoveSink, rtc::VideoSinkInterface<cricket::VideoFrame>*)
 PROXY_METHOD1(void, RegisterObserver, ObserverInterface*)
 PROXY_METHOD1(void, UnregisterObserver, ObserverInterface*)
 END_PROXY()
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_VIDEOSOURCEPROXY_H_