Remove update icon after user confirms download

ash/system/update/update_observer.h

Index: ash/system/update/update_observer.h
diff --git a/ash/system/update/update_observer.h b/ash/system/update/update_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..186402b7dff188957b038b144db05a0d660a1c33
--- /dev/null
+++ b/ash/system/update/update_observer.h
@@ -0,0 +1,19 @@
+// Copyright (c) 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 ASH_SYSTEM_UPDATE_UPDATE_OBSERVER_H_
+#define ASH_SYSTEM_UPDATE_UPDATE_OBSERVER_H_
+
+namespace ash {
+
+class UpdateObserver {
+ public:
+  virtual ~UpdateObserver() {}
+
+  virtual void OnUpdateOverCellularTargetSet(bool success) = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_UPDATE_UPDATE_OBSERVER_H_