Remove restart method from VideoTrackSourceInterface.

webrtc/api/videocapturertracksource.cc

Index: webrtc/api/videocapturertracksource.cc
diff --git a/webrtc/api/videocapturertracksource.cc b/webrtc/api/videocapturertracksource.cc
index 2bef1431de2c28b189ee97e8b40a74af3c270447..1bf4bea1d0d779ec93eff06e55b73f1ebd998572 100644
--- a/webrtc/api/videocapturertracksource.cc
+++ b/webrtc/api/videocapturertracksource.cc
@@ -376,19 +376,6 @@ void VideoCapturerTrackSource::Stop() {
       rtc::Bind(&cricket::VideoCapturer::Stop, video_capturer_.get()));
 }
 
-void VideoCapturerTrackSource::Restart() {
-  if (started_) {
-    return;
-  }
-  if (!worker_thread_->Invoke<bool>(
-          RTC_FROM_HERE, rtc::Bind(&cricket::VideoCapturer::StartCapturing,
-                                   video_capturer_.get(), format_))) {
-    SetState(kEnded);
-    return;
-  }
-  started_ = true;
-}
-
 // OnStateChange listens to the cricket::VideoCapturer::SignalStateChange.
 void VideoCapturerTrackSource::OnStateChange(
     cricket::VideoCapturer* capturer,