switchCamera() only calls stopCaptureOnCameraThread(), not stopCapture(), so the stopListening() call must be placed there. BUG=webrtc:5519,b/27497950 R=perkj@webrtc.org Review URL: https://codereview.webrtc.org/1770423002 . Cr-Commit-Position: refs/heads/master@{#11917}