Add unittests of ArcCustomNotificationView

ui/arc/notification/arc_notification_manager.cc

Index: ui/arc/notification/arc_notification_manager.cc
diff --git a/ui/arc/notification/arc_notification_manager.cc b/ui/arc/notification/arc_notification_manager.cc
index b4619203a7c13360a170dc3f7952d950bf5b83ef..60258c225ce0d3aea1ef2c979968ad7733c317ae 100644
--- a/ui/arc/notification/arc_notification_manager.cc
+++ b/ui/arc/notification/arc_notification_manager.cc
@@ -13,8 +13,7 @@
 #include "base/stl_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/arc/arc_bridge_service.h"
-#include "ui/arc/notification/arc_custom_notification_item.h"
-#include "ui/arc/notification/arc_notification_item.h"
+#include "ui/arc/notification/arc_notification_item_impl.h"
 
 namespace arc {
 
@@ -66,17 +65,10 @@ void ArcNotificationManager::OnNotificationPosted(
   const std::string& key = data->key;
   auto it = items_.find(key);
   if (it == items_.end()) {
-    // Old client with version < 5 would have use_custom_notification default,
-    // which is false.
-    const bool use_custom_notification = data->use_custom_notification;
     // Show a notification on the primary logged-in user's desktop.
     // TODO(yoshiki): Reconsider when ARC supports multi-user.
-    ArcNotificationItem* item =
-        use_custom_notification
-            ? new ArcCustomNotificationItem(this, message_center_, key,
-                                            main_profile_id_)
-            : new ArcNotificationItem(this, message_center_, key,
-                                      main_profile_id_);
+    ArcNotificationItem* item = new ArcNotificationItemImpl(

[hidehiko, 2017/03/02 15:38:17]

nit: maybe auto item = base::MakeUnique<>() then you just can move it at L73?

+        this, message_center_, key, main_profile_id_);
     // TODO(yoshiki): Use emplacement for performance when it's available.
     auto result = items_.insert(std::make_pair(key, base::WrapUnique(item)));
     DCHECK(result.second);