Deleted AppListViewDelegateObserver class (was unused).

ui/app_list/app_list_view_delegate.h

Index: ui/app_list/app_list_view_delegate.h
diff --git a/ui/app_list/app_list_view_delegate.h b/ui/app_list/app_list_view_delegate.h
index 6b3bbb7efdf93219276dc81cfa4695fb0a2f83af..b569af468ac66812bfdbf4decb23cec98ff4b1f3 100644
--- a/ui/app_list/app_list_view_delegate.h
+++ b/ui/app_list/app_list_view_delegate.h
@@ -146,10 +146,6 @@ class APP_LIST_EXPORT AppListViewDelegate {
 
   // Returns the list of users (for AppListMenu).
   virtual const Users& GetUsers() const = 0;
-
-  // Adds/removes an observer for profile changes.
-  virtual void AddObserver(AppListViewDelegateObserver* observer) {}
-  virtual void RemoveObserver(AppListViewDelegateObserver* observer) {}
 };
 
 }  // namespace app_list