Removing the section break UI support

This was an exploration for an alternative UI in all apps, where we
show section headers before every section. This was never released.

Change-Id: I2d36f1d078cc9a6f3ba6f0ec9655412182c9b016

src/com/android/launcher3/BaseRecyclerView.java

@@ -172,13 +172,6 @@ public abstract class BaseRecyclerView extends RecyclerView
         return mBackgroundPadding;
     }
 
-    /**
-     * Returns the scroll bar width when the user is scrolling.
-     */
-    public int getMaxScrollbarWidth() {
-        return mScrollbar.getThumbMaxWidth();
-    }
-
     /**
      * Returns the visible height of the recycler view:
      *   VisibleHeight = View height - top padding - bottom padding