ash: Add a bluetooth entry in the uber tray.

ash/system/bluetooth/bluetooth_observer.h

Index: ash/system/bluetooth/bluetooth_observer.h
diff --git a/ash/system/bluetooth/bluetooth_observer.h b/ash/system/bluetooth/bluetooth_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..3fe6a352b32374b7cec7d99deb86679cafd4646b
--- /dev/null
+++ b/ash/system/bluetooth/bluetooth_observer.h
@@ -0,0 +1,20 @@
+// Copyright (c) 2012 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_BLUETOOTH_BLUETOOTH_OBSERVER_H_
+#define ASH_SYSTEM_BLUETOOTH_BLUETOOTH_OBSERVER_H_
+#pragma once
+
+namespace ash {
+
+class BluetoothObserver {
+ public:
+  virtual ~BluetoothObserver() {}
+
+  virtual void OnBluetoothRefresh() = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_BLUETOOTH_BLUETOOTH_OBSERVER_H_