Add UpdateNotificationSize to MessageCenterController.

ui/message_center/views/message_list_view_unittest.cc

Index: ui/message_center/views/message_list_view_unittest.cc
diff --git a/ui/message_center/views/message_list_view_unittest.cc b/ui/message_center/views/message_list_view_unittest.cc
index a4dc8b12bd9bcfb8490b55e824ecd25f4d5b0544..730bda1798a2f2049cba92ba1f45bff9e8470695 100644
--- a/ui/message_center/views/message_list_view_unittest.cc
+++ b/ui/message_center/views/message_list_view_unittest.cc
@@ -152,6 +152,7 @@ class MessageListViewTest : public views::ViewsTestBase,
   void ClickOnNotificationButton(const std::string& notification_id,
                                  int button_index) override {}
   void ClickOnSettingsButton(const std::string& notification_id) override {}
+  void UpdateNotificationSize(const std::string& notification_id) override;
 
   // Widget to host a MessageListView.
   std::unique_ptr<views::Widget> widget_;
@@ -161,6 +162,12 @@ class MessageListViewTest : public views::ViewsTestBase,
   DISALLOW_COPY_AND_ASSIGN(MessageListViewTest);
 };
 
+void MessageListViewTest::UpdateNotificationSize(
+    const std::string& notification_id) {
+  // For this test, this method should not be invoked.
+  NOTREACHED();
+}
+
 /* Unit tests *****************************************************************/
 
 TEST_F(MessageListViewTest, AddNotification) {