Add ArcNotificationManager for new ARC notification

ui/arc/BUILD.gn

+# 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.
+
+import("//build/config/ui.gni")
+
+static_library("arc") {
+  sources = [
+    "notification/arc_notification_item.cc",
+    "notification/arc_notification_item.h",
+    "notification/arc_notification_manager.cc",
+    "notification/arc_notification_manager.h",
+  ]
+
+  deps = [
+    "//base",
+    "//components/arc:arc_bindings",
+    "//components/signin/core/account_id",
+    "//third_party/WebKit/public:blink_headers",
+    "//ui/gfx",
+    "//ui/message_center",
+  ]
+}