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

chrome/browser/extensions/api/web_request/web_request_api_helpers.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.
 
 // Helper classes and functions used for the WebRequest API.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_
 #define CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_
 
 #include <list>
@@ skipping 73 matching lines @@
 bool InDecreasingExtensionInstallationTimeOrder(
     const linked_ptr<EventResponseDelta>& a,
     const linked_ptr<EventResponseDelta>& b);
 
 // Converts a string to a list of integers, each in 0..255. Ownership
 // of the created list is passed to the caller.
 base::ListValue* StringToCharList(const std::string& s);
 
 // Converts a list of integer values between 0 and 255 into a string |*out|.
 // Returns true if the conversion was successful.
-bool CharListToString(base::ListValue* list, std::string* out);
+bool CharListToString(const base::ListValue* list, std::string* out);
 
 // The following functions calculate and return the modifications to requests
 // commanded by extension handlers. All functions take the id of the extension
 // that commanded a modification, the installation time of this extension (used
 // for defining a precedence in conflicting modifications) and whether the
 // extension requested to |cancel| the request. Other parameters depend on a
 // the signal handler. Ownership of the returned object is passed to the caller.
 
 EventResponseDelta* CalculateOnBeforeRequestDelta(
     const std::string& extension_id,
@@ skipping 86 matching lines @@
 
 // Returns whether |extension| may access |url| based on host permissions.
 // In addition to that access is granted to about: URLs and extension URLs
 // that are in the scope of |extension|.
 bool CanExtensionAccessURL(const extensions::Extension* extension,
                            const GURL& url);
 
 }  // namespace extension_web_request_api_helpers
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_