Merge "End the trace section in FrameTracker#cancel if it has begun" into sc-dev

     * Cancel the trace session of the CUJ.

     */

    public synchronized void cancel() {

        // The session is ongoing, end the trace session.

        // That means the cancel call is from external invocation, not from end().

        if (mBeginVsyncId != INVALID_ID && mEndVsyncId == INVALID_ID) {

        // We don't need to end the trace section if it never begun.

        if (mBeginVsyncId != INVALID_ID) {

            Trace.endAsyncSection(mSession.getName(), (int) mBeginVsyncId);

        }

        mCancelled = true;