Undo a rename of dbus::Message::GetSignature.

dbus/message.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 DBUS_MESSAGE_H_
 #define DBUS_MESSAGE_H_
 
 #include <string>
 #include <vector>
 #include <dbus/dbus.h>
@@ skipping 93 matching lines @@
   // SetSignature() does not exist as we cannot do it.
 
   // Gets the destination, the path, the interface, the member, etc.
   // If not set, an empty string is returned.
   std::string GetDestination();
   ObjectPath GetPath();
   std::string GetInterface();
   std::string GetMember();
   std::string GetErrorName();
   std::string GetSender();
-  std::string GetDataSignature();
+  std::string GetSignature();
   // Gets the serial and reply serial numbers. Returns 0 if not set.
   uint32 GetSerial();
   uint32 GetReplySerial();
 
   // Returns the string representation of this message. Useful for
   // debugging. The output is truncated as needed (ex. strings are truncated
   // if longer than a certain limit defined in the .cc file).
   std::string ToString();
 
  protected:
@@ skipping 359 matching lines @@
 
   Message* message_;
   DBusMessageIter raw_message_iter_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageReader);
 };
 
 }  // namespace dbus
 
 #endif  // DBUS_MESSAGE_H_