Remove a thread checker for a decoder thread from IncomingVideoStream.

webrtc/common_video/include/incoming_video_stream.h

 /*
  *  Copyright (c) 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.
  */
 
@@ skipping 24 matching lines @@
 
  private:
   enum { kEventStartupTimeMs = 10 };
   enum { kEventMaxWaitTimeMs = 100 };
   enum { kFrameRatePeriodMs = 1000 };
 
   void OnFrame(const VideoFrame& video_frame) override;
 
   rtc::ThreadChecker main_thread_checker_;
   rtc::ThreadChecker render_thread_checker_;
-  rtc::ThreadChecker decoder_thread_checker_;
 
   rtc::CriticalSection buffer_critsect_;
   rtc::PlatformThread incoming_render_thread_;
   std::unique_ptr<EventTimerWrapper> deliver_buffer_event_;
 
   rtc::VideoSinkInterface<VideoFrame>* const external_callback_;
   std::unique_ptr<VideoRenderFrames> render_buffers_
       GUARDED_BY(buffer_critsect_);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_VIDEO_INCLUDE_INCOMING_VIDEO_STREAM_H_