Merge "sysui: refactor for extensibility" into nyc-dev

    private boolean mStackScrollerOverscrolling;

    private boolean mQsExpansionFromOverscroll;

    private float mLastOverscroll;

    private boolean mQsExpansionEnabled = true;

    protected boolean mQsExpansionEnabled = true;

    private ValueAnimator mQsExpansionAnimator;

    private FlingAnimationUtils mFlingAnimationUtils;

    private int mStatusBarMinHeight;