Introduce new content APIs for persistent notifications.

content/shell/browser/layout_test/layout_test_notification_manager.cc

Index: content/shell/browser/layout_test/layout_test_notification_manager.cc
diff --git a/content/shell/browser/layout_test/layout_test_notification_manager.cc b/content/shell/browser/layout_test/layout_test_notification_manager.cc
index 7e7adf4c927bf1a4ec6139eaa8ab36c4e6ba7406..ce4e86b931e07409d8d492b5fd59360dea87b09d 100644
--- a/content/shell/browser/layout_test/layout_test_notification_manager.cc
+++ b/content/shell/browser/layout_test/layout_test_notification_manager.cc
@@ -84,6 +84,22 @@ void LayoutTestNotificationManager::DisplayNotification(
   notifications_[title]->NotificationDisplayed();
 }
 
+void LayoutTestNotificationManager::DisplayPersistentNotification(
+    BrowserContext* browser_context,
+    int64 service_worker_registration_id,
+    const ShowDesktopNotificationHostMsgParams& params,
+    int render_process_id) {
+  // TODO(peter): Make persistent notifications layout testable.
+  NOTIMPLEMENTED();
+}
+
+void LayoutTestNotificationManager::ClosePersistentNotification(
+    BrowserContext* browser_context,
+    const std::string& persistent_notification_id) {
+  // TODO(peter): Make persistent notifications layout testable.
+  NOTIMPLEMENTED();
+}
+
 void LayoutTestNotificationManager::SimulateClick(const std::string& title) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   auto iterator = notifications_.find(title);