Fix issue #6447773: Pulse does not run in JB (NPE in GestureDetector.onTouchEvent)

Change-Id: I20b6d58fa47851cf401bbeb16960d118bbd1d965

Author: Dianne Hackborn

core/java/android/view/GestureDetector.java

@@ -585,8 +585,12 @@ public boolean onTouchEvent(MotionEvent ev) {
             }
             // Hold the event we obtained above - listeners may have changed the original.
             mPreviousUpEvent = currentUpEvent;
-            mVelocityTracker.recycle();
-            mVelocityTracker = null;
+            if (mVelocityTracker != null) {
+                // This may have been cleared when we called out to the
+                // application above.
+                mVelocityTracker.recycle();
+                mVelocityTracker = null;
+            }
             mIsDoubleTapping = false;
             mHandler.removeMessages(SHOW_PRESS);
             mHandler.removeMessages(LONG_PRESS);