[Predictive Back] Fix small bottom gap in widget to home animation

The bug was caused by a math problem. The extrat bottom offset should be

 offset = (H / 0.9 - H) / 2

Fix: b/269393854
Test: manual
Change-Id: Ia4d6b3f2ecb53b82d6779cd385ce4d7ca3c16113
diff --git a/src/com/android/launcher3/views/AbstractSlideInView.java b/src/com/android/launcher3/views/AbstractSlideInView.java
index e2f1c04..ebae00d 100644
--- a/src/com/android/launcher3/views/AbstractSlideInView.java
+++ b/src/com/android/launcher3/views/AbstractSlideInView.java
@@ -236,8 +236,8 @@
     /** Return extra space revealed during predictive back animation. */
     @Px
     protected int getBottomOffsetPx() {
-        return (int) (getMeasuredHeight()
-                * (1 - PREDICTIVE_BACK_MIN_SCALE) / 2);
+        final int height = getMeasuredHeight();
+        return (int) ((height / PREDICTIVE_BACK_MIN_SCALE - height) / 2);
     }
 
     /**