Fixing issue where the prediction bar could be misplaced after installing an app.

- When the adapter changes, we didn't update the scroll position that the prediction
  bar tracks, which caused it to be misplaced.  This forces a refresh of that scroll
  position to the current state whenever an app is removed or added.

src/com/android/launcher3/AppsContainerView.java

@@ -82,11 +82,11 @@ public class AppsContainerView extends BaseContainerView implements DragSource,
     private int mNumAppsPerRow;
     private int mNumPredictedAppsPerRow;
     // This coordinate is relative to this container view
-    private Point mBoundsCheckLastTouchDownPos = new Point(-1, -1);
+    private final Point mBoundsCheckLastTouchDownPos = new Point(-1, -1);
     // This coordinate is relative to its parent
-    private Point mIconLastTouchPos = new Point();
-    // This coordinate is used to proxy click and long-click events
-    private Point mPredictionIconTouchDownPos = new Point();
+    private final Point mIconLastTouchPos = new Point();
+    // This coordinate is used to proxy click and long-click events to the prediction bar icons
+    private final Point mPredictionIconTouchDownPos = new Point();
     private int mContentMarginStart;
     // Normal container insets
     private int mContainerInset;