UdfpsController: Call onFingerDown on action down events

                    // We need to persist its ID to track it during ACTION_MOVE that could include

                    // data for many other pointers because of multi-touch support.

                    mActivePointerId = event.getPointerId(0);

                    final int idx = mActivePointerId == -1

                            ? event.getPointerId(0)

                            : event.findPointerIndex(mActivePointerId);

                    mVelocityTracker.addMovement(event);

                    onFingerDown((int) event.getRawX(), (int) event.getRawY(),

                            (int) event.getTouchMinor(idx), (int) event.getTouchMajor(idx));

                    handled = true;

                }

                if ((withinSensorArea || fromUdfpsView) && shouldTryToDismissKeyguard()) {