Fix nested pre-scrolling delta magnitude

The framework bug causing a mis-signed delta was fixed, so
update the app-side workaround accordingly.

https://googleplex-android-review.git.corp.google.com/#/c/498315/

Change-Id: Id7272de056870a9272ac3d8bef8ab95c2275f74d
diff --git a/src/com/android/dialer/widget/OverlappingPaneLayout.java b/src/com/android/dialer/widget/OverlappingPaneLayout.java
index 0b11e88..b6b9ec7 100644
--- a/src/com/android/dialer/widget/OverlappingPaneLayout.java
+++ b/src/com/android/dialer/widget/OverlappingPaneLayout.java
@@ -916,8 +916,8 @@
             Log.d(TAG, "onNestedPreScroll: " + dy);
         }
         mInNestedPreScrollDownwards =
-                mChildCannotConsumeScroll && dy > 0 && mSlideOffsetPx <= mIntermediateOffset;
-        mDragHelper.processNestedScroll(mSlideableView, 0, dy, consumed);
+                mChildCannotConsumeScroll && dy < 0 && mSlideOffsetPx <= mIntermediateOffset;
+        mDragHelper.processNestedScroll(mSlideableView, 0, -dy, consumed);
     }
 
     @Override
@@ -928,7 +928,6 @@
         }
         mChildCannotConsumeScroll = false;
         mInNestedPreScrollDownwards = false;
-        // We need to flip dyUnconsumed here, because its magnitude is reversed. b/14585990
         mDragHelper.processNestedScroll(mSlideableView, 0, -dyUnconsumed, null);
     }