Revert "Revert "Updating the scroll calculation from recyclerView to avoid view inflation""

Test: ABTD
https://android-build.googleplex.com/builds/abtd/run/L52600000956969786

This reverts commit cee6ddf3de.

Reason for revert: Fixed in ag/20239136

Change-Id: I0e8446e66d9a86a94b40fcbd6de14da07abe8e5c

src/com/android/launcher3/allapps/FloatingHeaderView.java

@@ -68,7 +68,7 @@ public class FloatingHeaderView extends LinearLayout implements
                         mAnimator.cancel();
                     }
 
-                    int current = -mCurrentRV.getCurrentScrollY();
+                    int current = -mCurrentRV.computeVerticalScrollOffset();
                     boolean headerCollapsed = mHeaderCollapsed;
                     moved(current);
                     applyVerticalMove();