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

chrome/browser/extensions/extension_override_apitest.cc

 // 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.
 
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_web_ui.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/prefs/scoped_user_pref_update.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/web_contents.h"
 
 using content::WebContents;
 
 class ExtensionOverrideTest : public ExtensionApiTest {
  protected:
   bool CheckHistoryOverridesContainsNoDupes() {
     // There should be no duplicate entries in the preferences.
     const DictionaryValue* overrides =
         browser()->profile()->GetPrefs()->GetDictionary(
             ExtensionWebUI::kExtensionURLOverrides);
 
-    ListValue* values = NULL;
+    const ListValue* values = NULL;
     if (!overrides->GetList("history", &values))
       return false;
 
     std::set<std::string> seen_overrides;
     for (size_t i = 0; i < values->GetSize(); ++i) {
       std::string value;
       if (!values->GetString(i, &value))
         return false;
 
       if (seen_overrides.find(value) != seen_overrides.end())
@@ skipping 93 matching lines @@
                                 ExtensionWebUI::kExtensionURLOverrides);
     update.Get()->Set("history", list);
   }
 
   ASSERT_FALSE(CheckHistoryOverridesContainsNoDupes());
 
   ASSERT_TRUE(LoadExtension(test_data_dir_.AppendASCII("override/history")));
 
   ASSERT_TRUE(CheckHistoryOverridesContainsNoDupes());
 }