Introduce a new API to handle native notification clicks

chrome/browser/notifications/notification_handler.h

+// Copyright 2016 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 CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_HANDLER_H_
+#define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_HANDLER_H_
+
+#include <memory>
+#include <string>
+
+class NotificationDelegate;
+class Profile;
+
+// Interface that enables the different kind of notifications to process
+// operations coming from the user.
+class NotificationHandler {
+ public:
+  virtual ~NotificationHandler() {}
+
+  // Process notification close events.
+  virtual void OnClose(Profile* profile,
+                       const std::string& origin,
+                       const std::string& notification_id,
+                       bool by_user) = 0;
+
+  // Process cliks to a notification or its buttons, depending on
+  // |action_index|.
+  virtual void OnClick(Profile* profile,
+                       const std::string& origin,
+                       const std::string& notification_id,
+                       int action_index) = 0;
+
+  // Open notification settings.
+  virtual void OpenSettings(Profile* profile) = 0;
+
+  // Registers a |delegate| object with this handler.
+  virtual void RegisterNotification(const std::string& notification_id,
+                                    NotificationDelegate* delegate) = 0;
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_HANDLER_H_