Using velocity tracker for computing the velocity of motion events

Change-Id: I14f2f970825a2936f4bb285834405d67daf8667c

src/com/android/launcher3/touch/AbstractStateChangeTouchController.java

@@ -256,7 +256,7 @@ public abstract class AbstractStateChangeTouchController
     }
 
     @Override
-    public boolean onDrag(float displacement, float velocity) {
+    public boolean onDrag(float displacement) {
         float deltaProgress = mProgressMultiplier * (displacement - mDisplacementShift);
         float progress = deltaProgress + mStartProgress;
         updateProgress(progress);