This CL replaces the function SurfaceTextureHelper.setListener() that
could only be called once with the functions startListening() and
stopListening() that can be called multiple times. This is necessary
when the SurfaceTextureHelper will be passed to the VideoCapturerAndroid
in startCapture(). startListening() will be called in startCapture() and
stopListening() in stopCapture().
BUG=webrtc:5519
Review URL: https://codereview.webrtc.org/1755573002
Cr-Commit-Position: refs/heads/master@{#11855}
81e8e374ec