Merge "Fix docs for FrameMetrics.TOTAL_DURATION"

     * and be issued to the display subsystem.

     * </p>

     * <p>

     * Equal to the sum of the values of all other time-valued metric

     * identifiers.

     * The total duration is the difference in time between when the frame

     * began and when it ended. This value may not be exactly equal to the

     * sum of the values of all other time-valued metric identifiers because

     * some stages may happen concurrently.

     * </p>

     */

    public static final int TOTAL_DURATION = 8;