Report wallpaper offset to the wallpaper, use this in the image wallpaper.

Wallpapers can now be just the size of the screen, and get told when their
scroll position should change to do the updating on their own.
diff --git a/core/java/android/view/ViewRoot.java b/core/java/android/view/ViewRoot.java
index 216fc5e..4623bb5 100644
--- a/core/java/android/view/ViewRoot.java
+++ b/core/java/android/view/ViewRoot.java
@@ -2858,6 +2858,9 @@
                 }
             }
         }
+        
+        public void dispatchWallpaperOffsets(float x, float y) {
+        }
     }
 
     /**