Add layout tests for ServiceWorker's notificationclose event.

components/test_runner/web_test_delegate.h

Index: components/test_runner/web_test_delegate.h
diff --git a/components/test_runner/web_test_delegate.h b/components/test_runner/web_test_delegate.h
index d5d67e4eb9c6dcc89e7f6889b743224314884410..9aa52902387ac4dd284e21911e0c05675b74be92 100644
--- a/components/test_runner/web_test_delegate.h
+++ b/components/test_runner/web_test_delegate.h
@@ -157,6 +157,8 @@ class WebTestDelegate {
   // Controls Web Notifications.
   virtual void SimulateWebNotificationClick(const std::string& title,
                                             int action_index) = 0;
+  virtual void SimulateWebNotificationClose(const std::string& title,
+                                            bool by_user) = 0;
 
   // Controls the device scale factor of the main WebView for hidpi tests.
   virtual void SetDeviceScaleFactor(float factor) = 0;