Update AudioRecord comments to match AudioTrack

        EVENT_MORE_DATA = 0,        // Request to read available data from buffer.

                                    // If this event is delivered but the callback handler

                                    // does not want to read the available data, the handler must

                                    // explicitly

                                    // ignore the event by setting frameCount to zero.

                                    // explicitly ignore the event by setting frameCount to zero.

        EVENT_OVERRUN = 1,          // Buffer overrun occurred.

        EVENT_MARKER = 2,           // Record head is at the specified marker position

                                    // (See setMarkerPosition()).

                                    // voluntary invalidation by mediaserver, or mediaserver crash.

    };

    /* Client should declare Buffer on the stack and pass address to obtainBuffer()

    /* Client should declare a Buffer and pass address to obtainBuffer()

     * and releaseBuffer().  See also callback_t for EVENT_MORE_DATA.

     */

    public:

        // FIXME use m prefix

        size_t      frameCount;     // number of sample frames corresponding to size;

                                    // on input it is the number of frames available,

                                    // on output is the number of frames actually drained

                                    // (currently ignored but will make the primary field in future)

                                    // on input to obtainBuffer() it is the number of frames desired,

                                    // on output from obtainBuffer() it is the number of available

                                    //    frames to be read

                                    // on input to releaseBuffer() it is currently ignored

        size_t      size;           // input/output in bytes == frameCount * frameSize

                                    // on output is the number of bytes actually drained

                                    // FIXME this is redundant with respect to frameCount,

                                    // and TRANSFER_OBTAIN mode is broken for 8-bit data

                                    // since we don't define the frame format

                                    // on input to obtainBuffer() it is ignored

                                    // on output from obtainBuffer() it is the number of available

                                    //    bytes to be read, which is frameCount * frameSize

                                    // on input to releaseBuffer() it is the number of bytes to

                                    //    release

                                    // FIXME This is redundant with respect to frameCount.  Consider

                                    //    removing size and making frameCount the primary field.

        union {

            void*       raw;

            short*      i16;        // signed 16-bit

            int8_t*     i8;         // unsigned 8-bit, offset by 0x80

                                    // input to obtainBuffer(): unused, output: pointer to buffer

        };

    };

     *                     be larger if the requested size is not compatible with current audio HAL

     *                     latency.  Zero means to use a default value.

     * cbf:                Callback function. If not null, this function is called periodically

     *                     to consume new data and inform of marker, position updates, etc.

     *                     to consume new data in TRANSFER_CALLBACK mode

     *                     and inform of marker, position updates, etc.

     * user:               Context for use by the callback receiver.

     * notificationFrames: The callback function is called each time notificationFrames PCM

     *                     frames are ready in record track output buffer.

            status_t    initCheck() const   { return mStatus; }

    /* Returns this track's estimated latency in milliseconds.

     * This includes the latency due to AudioRecord buffer size,

     * This includes the latency due to AudioRecord buffer size, resampling if applicable,

     * and audio hardware driver.

     */

            uint32_t    latency() const     { return mLatency; }

     */

            int    getSessionId() const { return mSessionId; }

    /* Obtains a buffer of up to "audioBuffer->frameCount" full frames.

    /* Public API for TRANSFER_OBTAIN mode.

     * Obtains a buffer of up to "audioBuffer->frameCount" full frames.

     * After draining these frames of data, the caller should release them with releaseBuffer().

     * If the track buffer is not empty, obtainBuffer() returns as many contiguous

     * full frames as are available immediately.

     * Buffer fields

     * On entry:

     *  frameCount  number of frames requested

     *  size        ignored

     *  raw         ignored

     * After error return:

     *  frameCount  0

     *  size        0

void AudioRecord::releaseBuffer(Buffer* audioBuffer)

{

    // all TRANSFER_* are valid

    // FIXME add error checking on mode, by adding an internal version

    size_t stepCount = audioBuffer->size / mFrameSize;

    if (stepCount == 0) {