arc: Show custom notification via notification surface

ui/arc/notification/arc_notification_surface_manager.h

Index: ui/arc/notification/arc_notification_surface_manager.h
diff --git a/ui/arc/notification/arc_notification_surface_manager.h b/ui/arc/notification/arc_notification_surface_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..4a5d6f503b59dd923d9ee82d61c4215ccb6256f9
--- /dev/null
+++ b/ui/arc/notification/arc_notification_surface_manager.h
@@ -0,0 +1,60 @@
+// 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 UI_ARC_NOTIFICATION_ARC_NOTIFICATION_SURFACE_MANAGER_
+#define UI_ARC_NOTIFICATION_ARC_NOTIFICATION_SURFACE_MANAGER_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+#include "base/observer_list.h"
+#include "components/exo/notification_surface_manager.h"
+
+namespace arc {
+
+// Keeps track of NotificationSurface.
+class ArcNotificationSurfaceManager : public exo::NotificationSurfaceManager {
+ public:
+  class Observer {
+   public:
+    // Invoked when a notification surface is added to the registry.
+    virtual void OnNotificationSurfaceAdded(
+        exo::NotificationSurface* surface) = 0;
+
+    // Invoked when a notification surface is removed from the registry.
+    virtual void OnNotificationSurfaceRemoved(
+        exo::NotificationSurface* surface) = 0;
+
+   protected:
+    virtual ~Observer() = default;
+  };
+
+  ArcNotificationSurfaceManager();
+  ~ArcNotificationSurfaceManager() override;
+
+  static ArcNotificationSurfaceManager* Get();
+
+  // exo::NotificationSurfaceManager:
+  exo::NotificationSurface* GetSurface(
+      const std::string& notification_id) const override;
+  void AddSurface(exo::NotificationSurface* surface) override;
+  void RemoveSurface(exo::NotificationSurface* surface) override;
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ private:
+  using NotificationSurfaceMap =
+      std::map<std::string, exo::NotificationSurface*>;
+  NotificationSurfaceMap notification_surface_map_;
+
+  base::ObserverList<Observer> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcNotificationSurfaceManager);
+};
+
+}  // namespace arc
+
+#endif  // UI_ARC_NOTIFICATION_ARC_NOTIFICATION_SURFACE_MANAGER_