Change setScrollVertically to protected to make scroll work in subclasses.

setScrollVertically is called by the animator and if it has no access to the
method in the subclass.  This will allow 3P app to extend the view.

Change-Id: I976355168fe1ed4e1f70b66aaab27ca16214dc05

samples/wearable/AgendaData/Application/proguard-rules.txt

@@ -23,6 +23,6 @@
 
 -keep class android.support.wearable.view.WearableListView {
   private void setScrollAnimator(int);
-  private void setScrollVertically(int);
+  protected void setScrollVertically(int);
 }
 

samples/wearable/Flashlight/Wearable/proguard-rules.txt

@@ -11,7 +11,7 @@
 
 -keep class android.support.wearable.view.WearableListView {
   private void setScrollAnimator(int);
-  private void setScrollVertically(int);
+  protected void setScrollVertically(int);
 }
 -keep class android.support.wearable.view.WearableListView.ViewHolder {
   private void setFocusPaddingTop(int);