Merge "SurfaceFlinger: expectedVsyncTimestamp can be 0"

/*

 * Returns whether a given vsync timestamp is in phase with a vsync divider.

 * For example, if the vsync timestamps are (0,16,32,48):

 * isVSyncInPhase(0, 2) = true

 * isVSyncInPhase(16, 2) = false

 * isVSyncInPhase(32, 2) = true

 * For example, if the vsync timestamps are (16,32,48,64):

 * isVSyncInPhase(16, 2) = true

 * isVSyncInPhase(32, 2) = false

 * isVSyncInPhase(48, 2) = true

 */

bool VSyncPredictor::isVSyncInPhase(nsecs_t timePoint, int divider) const {

    struct VsyncError {

        bool operator<(const VsyncError& other) const { return error < other.error; }

    };

    std::lock_guard lock(mMutex);

    if (divider <= 1) {

    if (divider <= 1 || timePoint == 0) {

        return true;

    }

    std::lock_guard lock(mMutex);

    const nsecs_t period = mRateMap[mIdealPeriod].slope;

    const nsecs_t justBeforeTimePoint = timePoint - period / 2;

    const nsecs_t dividedPeriod = mIdealPeriod / divider;