Deprecate per notification type delegates.

content/public/browser/desktop_notification_delegate.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef CONTENT_PUBLIC_BROWSER_DESKTOP_NOTIFICATION_DELEGATE_H_
-#define CONTENT_PUBLIC_BROWSER_DESKTOP_NOTIFICATION_DELEGATE_H_
-
-namespace content {
-
-// A delegate used by ContentBrowserClient::ShowDesktopNotification to report
-// the result of a desktop notification.
-class DesktopNotificationDelegate {
- public:
-  virtual ~DesktopNotificationDelegate() {}
-
-  // The notification was shown.
-  virtual void NotificationDisplayed() = 0;
-
-  // The notification was closed.
-  virtual void NotificationClosed() = 0;
-
-  // The user clicked on the notification.
-  virtual void NotificationClick() = 0;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_PUBLIC_BROWSER_DESKTOP_NOTIFICATION_DELEGATE_H_