Adding vibration after successful dock/undock gesture.

import android.graphics.Region.Op;

import android.hardware.display.DisplayManager;

import android.os.Bundle;

import android.os.Vibrator;

import android.util.AttributeSet;

import android.view.Display;

import android.view.DisplayInfo;

import android.view.GestureDetector;

import android.view.GestureDetector.OnDoubleTapListener;

import android.view.GestureDetector.SimpleOnGestureListener;

import android.view.HapticFeedbackConstants;

import android.view.MotionEvent;

import android.view.PointerIcon;

import android.view.VelocityTracker;

import android.view.ViewConfiguration;

import android.view.ViewTreeObserver.InternalInsetsInfo;

import android.view.ViewTreeObserver.OnComputeInternalInsetsListener;

import android.view.ViewTreeObserver.OnGlobalLayoutListener;

import android.view.WindowInsets;

import android.view.WindowManager;

import android.view.accessibility.AccessibilityNodeInfo;

        mEntranceAnimationRunning = true;

        resizeStack(position, mSnapAlgorithm.getMiddleTarget().position,

                mSnapAlgorithm.getMiddleTarget());

        // Vibrate after docking

        performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);

    }

    public final void onBusEvent(RecentsDrawnEvent drawnEvent) {

            // Don't start immediately - give a little bit time to settle the drag resize change.

            stopDragging(getCurrentPosition(), target, 336 /* duration */, 100 /* startDelay */,

                    Interpolators.TOUCH_RESPONSE);

            // Vibrate after undocking

            performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);

        }

    }

}