Add unittests of ArcCustomNotificationView

ui/arc/notification/arc_notification_surface.h

Index: ui/arc/notification/arc_notification_surface.h
diff --git a/ui/arc/notification/arc_notification_surface.h b/ui/arc/notification/arc_notification_surface.h
new file mode 100644
index 0000000000000000000000000000000000000000..7297b96871909ee6c2b2205cfbf05a18273721a5
--- /dev/null
+++ b/ui/arc/notification/arc_notification_surface.h
@@ -0,0 +1,39 @@
+// Copyright 2017 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_H_
+#define UI_ARC_NOTIFICATION_ARC_NOTIFICATION_SURFACE_H_
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace aura {
+class Window;
+}
+
+namespace views {
+class NativeViewHost;
+}
+
+namespace arc {
+
+// Handles notification surface role of a given surface.
+class ArcNotificationSurface {
+ public:
+  virtual ~ArcNotificationSurface() = default;
+
+  virtual gfx::Size GetSize() const = 0;
+
+  virtual void AttachWindow(views::NativeViewHost* native_view_host) = 0;
+
+  virtual aura::Window* GetWindow() const = 0;
+  virtual const std::string& GetNotificationId() const = 0;
+};
+
+}  // namespace arc
+
+#endif  // UI_ARC_NOTIFICATION_ARC_NOTIFICATION_SURFACE_H_