Cleanup shelf initialization and observation.

ash/shelf/shelf_delegate.h

Index: ash/shelf/shelf_delegate.h
diff --git a/ash/shelf/shelf_delegate.h b/ash/shelf/shelf_delegate.h
index 32f08a3aa221b6d50eb3fb7b330a4ae8c0689c75..16e041c4e454904b0b68dcd2282c408ac5513c33 100644
--- a/ash/shelf/shelf_delegate.h
+++ b/ash/shelf/shelf_delegate.h
@@ -25,6 +25,12 @@ class ASH_EXPORT ShelfDelegate {
   // exists.
   virtual void OnShelfDestroyed(Shelf* shelf) = 0;
 
+  // Called when |shelf|'s alignment changes.
+  virtual void OnShelfAlignmentChanged(Shelf* shelf) = 0;
+
+  // Called when |shelf|'s auto-hide behavior changes.
+  virtual void OnShelfAutoHideBehaviorChanged(Shelf* shelf) = 0;
+
   // Get the shelf ID from an application ID.
   virtual ShelfID GetShelfIDForAppID(const std::string& app_id) = 0;