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>
+
+#include "chrome/browser/notifications/notification_common.h"
+
+class NotificationDelegate;
+class Profile;
+
+// Interface that enables the different kind of notifications
+// to process operations coming from the user.
+// Whenever a notification is clicked or closed or a button is pressed
+// the right kind of NotificationHandler will deal with the operation.

[Peter Beverloo, 2016/07/05 14:25:34]

nit: remove lines 18/19- it's partly implied, partly not the responsibility of
the handler.

[Miguel Garcia, 2016/07/05 17:12:52]

Done.

+class NotificationHandler {
+ public:
+  virtual ~NotificationHandler() {}
+
+  // Close a notification. This method works both for user generated
+  // close events or for notifications closed programatically.
+  // This is driven by the |by_user| flag.

[Peter Beverloo, 2016/07/05 14:25:34]

This method observes notifications being closed for the specific type of handler
(so is informed after-the-fact), but this comment makes me think this method
*closes* notifications with the given details.

Please consider naming this OnClose or DidClose to distinguish. Dito re: the
other methods in this class.

[Miguel Garcia, 2016/07/05 17:12:53]

Added the On* prefix

+  virtual void Close(Profile* profile,
+                     const std::string& origin,
+                     const std::string& notification_id,
+                     bool by_user) = 0;
+
+  // Click on a notification or one of its buttons, depending on |action_index|.
+  virtual void Click(Profile* profile,
+                     const std::string& origin,
+                     const std::string& notification_id,
+                     int action_index) = 0;
+
+  // Open notification settings.
+  virtual void Settings(Profile* profile) = 0;

[Peter Beverloo, 2016/07/05 14:25:34]

nit: OpenSettings

[Miguel Garcia, 2016/07/05 17:12:52]

Done.

+
+  // Registers a |Notification| object with this handler.
+  virtual void RegisterNotification(const std::string& notification_id,
+                                    NotificationDelegate* delegate) = 0;
+
+  // Return the kind of notifications the class knows how to handle.
+  virtual NotificationCommon::Type NotificationType() = 0;
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_HANDLER_H_