Prevent extra animation when scrolling the recycler view.

Change-Id: I362b557ae63a2cbef77ebf7fac9a7a27adeabb49
diff --git a/src/com/android/launcher3/BaseRecyclerViewFastScrollBar.java b/src/com/android/launcher3/BaseRecyclerViewFastScrollBar.java
index 96e994b..6ff2ec6 100644
--- a/src/com/android/launcher3/BaseRecyclerViewFastScrollBar.java
+++ b/src/com/android/launcher3/BaseRecyclerViewFastScrollBar.java
@@ -169,10 +169,12 @@
                 break;
             case MotionEvent.ACTION_UP:
             case MotionEvent.ACTION_CANCEL:
-                mIsDragging = false;
                 mTouchOffset = 0;
-                mPopup.animateVisibility(false);
-                animateScrollbar(false);
+                if (mIsDragging) {
+                    mIsDragging = false;
+                    mPopup.animateVisibility(false);
+                    animateScrollbar(false);
+                }
                 break;
         }
     }