Merge "audio: fix race when stopping a stream" into sc-dev

            AudioTrack::Buffer *audioBuffer = static_cast<AudioTrack::Buffer *>(info);

            if (getState() == AAUDIO_STREAM_STATE_DISCONNECTED) {

                ALOGW("processCallbackCommon() data, stream disconnected");

                // This will kill the stream and prevent it from being restarted.

                // That is OK because the stream is disconnected.

                audioBuffer->size = SIZE_STOP_CALLBACKS;

            } else if (!mCallbackEnabled.load()) {

                ALOGW("processCallbackCommon() no data because callback disabled");

                audioBuffer->size = SIZE_STOP_CALLBACKS;

                ALOGW("processCallbackCommon() no data because callback disabled, set size=0");

                // Do NOT use SIZE_STOP_CALLBACKS here because that will kill the stream and

                // prevent it from being restarted. This can occur because of a race condition

                // caused by Legacy callbacks running after the track is "stopped".

                audioBuffer->size = 0;

            } else {

                if (audioBuffer->frameCount == 0) {

                    ALOGW("processCallbackCommon() data, frameCount is zero");