Added UMA Metrics for SMS UI in the status area.

ash/common/system/chromeos/network/tray_sms.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_COMMON_SYSTEM_CHROMEOS_NETWORK_TRAY_SMS_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_TRAY_SMS_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 25 matching lines @@
  protected:
   class SmsDefaultView;
   class SmsDetailedView;
   class SmsMessageView;
   class SmsNotificationView;
 
   // Gets the most recent message. Returns false if no messages or unable to
   // retrieve the numebr and text from the message.
   bool GetLatestMessage(size_t* index, std::string* number, std::string* text);
 
-  // Removes message at |index| from message list.
-  void RemoveMessage(size_t index);
+  // Removes message at |index| from message list. Returns true if |index| was
+  // valid and a message was removed.
+  bool RemoveMessage(size_t index);
 
   // Called when sms messages have changed (through
   // chromeos::NetworkSmsHandler::Observer).
   void Update(bool notify);
 
   base::ListValue& messages() { return messages_; }
 
  private:
   SmsDefaultView* default_;
   SmsDetailedView* detailed_;
   SmsNotificationView* notification_;
   base::ListValue messages_;
 
   DISALLOW_COPY_AND_ASSIGN(TraySms);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_TRAY_SMS_H_