Re-factor TraySms to use ash::SmsObserver instead of NetoworkSmsHandler.

ash/system/network/sms_observer.h

+// 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_NETWORK_SMS_OBSERVER_H
+#define ASH_SYSTEM_NETWORK_SMS_OBSERVER_H
+#pragma once
+
+#include "base/string16.h"
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace ash {
+
+const char kSmsNumberKey[] = "number";
+const char kSmsTextKey[] = "text";
+
+class SmsObserver {
+ public:
+  virtual ~SmsObserver() {}
+
+  virtual void AddMessage(const base::DictionaryValue& message) = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_NETWORK_SMS_OBSERVER_H