Removed unused async_invoker_ in WebRtcVideoCapturer

webrtc/media/engine/webrtcvideocapturer.h

 /*
  *  Copyright (c) 2004 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.
  */
 
@@ skipping 60 matching lines @@
   // directly from OnIncomingCapturedFrame.
   // TODO(tommi): Remove this workaround when we've updated the WebRTC capturers
   // to follow the same contract.
   void SignalFrameCapturedOnStartThread(const webrtc::VideoFrame& frame);
 
   std::unique_ptr<WebRtcVcmFactoryInterface> factory_;
   rtc::scoped_refptr<webrtc::VideoCaptureModule> module_;
   int captured_frames_;
   std::vector<uint8_t> capture_buffer_;
   rtc::Thread* start_thread_;  // Set in Start(), unset in Stop();
-
-  std::unique_ptr<rtc::AsyncInvoker> async_invoker_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_WEBRTC_WEBRTCVIDEOCAPTURER_H_