precondition: preview is running
-- call startRecording()
-- a preview frame arrives, causing the record callback to be called, and then
blocks on mRecordWait.wait()
-- call stopRecording(), which sets mReleasedRecordingFrame and signals
mRecordWait;
-- call startRecording(), which clears mReleasedRecordingFrame;
-- receivePreviewFrame() wakes up, checks mReleasedRecordingFrame, and
blocks again on mRecordWait.wait(), without having notified the client.
Signed-off-by: Iliyan Malchev <malchev@google.com>
32b7f2804e