Introduce a new API to handle native notification clicks

chrome/browser/notifications/non_persistent_notification_handler.h

Index: chrome/browser/notifications/non_persistent_notification_handler.h
diff --git a/chrome/browser/notifications/non_persistent_notification_handler.h b/chrome/browser/notifications/non_persistent_notification_handler.h
new file mode 100644
index 0000000000000000000000000000000000000000..51b8d3629658f577eabefdf812837636d9c9e410
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+++ b/chrome/browser/notifications/non_persistent_notification_handler.h
@@ -0,0 +1,46 @@
+// 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_NON_PERSISTENT_NOTIFICATION_HANDLER_H_
+#define CHROME_BROWSER_NOTIFICATIONS_NON_PERSISTENT_NOTIFICATION_HANDLER_H_
+
+#include <unordered_map>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/browser/notifications/notification_handler.h"
+
+class NotificationDelegate;
+
+// NotificationHandler implementation for non persistent notifications.
+class NonPersistentNotificationHandler : public NotificationHandler {
+ public:
+  NonPersistentNotificationHandler();
+  ~NonPersistentNotificationHandler() override;
+
+  // NotificationHandler implementation
+  void OnClose(Profile* profile,
+               const std::string& origin,
+               const std::string& notification_id,
+               bool by_user) override;
+
+  void OnClick(Profile* profile,
+               const std::string& origin,
+               const std::string& notification_id,
+               int action_index) override;
+
+  void OpenSettings(Profile* profile) override;
+
+  void RegisterNotification(const std::string& notification_id,
+                            NotificationDelegate* delegate) override;
+
+ private:
+  // map of delegate objects keyed by notification id.
+  std::unordered_map<std::string, scoped_refptr<NotificationDelegate>>
+      notifications_;
+
+  DISALLOW_COPY_AND_ASSIGN(NonPersistentNotificationHandler);
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_NON_PERSISTENT_NOTIFICATION_HANDLER_H_