Correct const accessors in base/values.(h|cc)

chrome/test/webdriver/commands/source_command.h

 // Copyright (c) 2011 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 CHROME_TEST_WEBDRIVER_COMMANDS_SOURCE_COMMAND_H_
 #define CHROME_TEST_WEBDRIVER_COMMANDS_SOURCE_COMMAND_H_
 
 #include <string>
 #include <vector>
 
 #include "chrome/test/webdriver/commands/webdriver_command.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace webdriver {
 
 class Response;
 
 // Gets the page source. See:
 // http://code.google.com/p/selenium/wiki/JsonWireProtocol#/session/:sessionId/source
 class SourceCommand : public WebDriverCommand {
  public:
   SourceCommand(const std::vector<std::string>& path_segments,
-                const base::DictionaryValue* const parameters);
+                base::DictionaryValue* const parameters);
   virtual ~SourceCommand();
 
   virtual bool DoesGet() OVERRIDE;
   virtual void ExecuteGet(Response* const response) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SourceCommand);
 };
 
 }  // namespace webdriver
 
 #endif  // CHROME_TEST_WEBDRIVER_COMMANDS_SOURCE_COMMAND_H_