Add UpdateNotificationSize to MessageCenterController.

ui/message_center/views/custom_notification_view_unittest.cc

Index: ui/message_center/views/custom_notification_view_unittest.cc
diff --git a/ui/message_center/views/custom_notification_view_unittest.cc b/ui/message_center/views/custom_notification_view_unittest.cc
index 5c82693921e2299ab5a1bed9a91a22b2f0af1154..c90b1ac06932b8bd6bb0ef9a0ff36366a18a79a2 100644
--- a/ui/message_center/views/custom_notification_view_unittest.cc
+++ b/ui/message_center/views/custom_notification_view_unittest.cc
@@ -146,6 +146,11 @@ class TestMessageCenterController : public MessageCenterController {
     NOTREACHED();
   }
 
+  void UpdateNotificationSize(const std::string& notification_id) override {
+    // For this test, this method should not be invoked.
+    NOTREACHED();
+  }
+
   bool IsRemoved(const std::string& notification_id) const {
     return (removed_ids_.find(notification_id) != removed_ids_.end());
   }