[Translate] Factor out access to Accept-Languages

components/translate/core/browser/translate_prefs.cc

 // Copyright 2014 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 "components/translate/core/browser/translate_prefs.h"
 
 #include <set>
 
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
@@ skipping 340 matching lines @@
     prefs_->GetDictionary(kPrefTranslateTooOftenDeniedForLanguage);
   bool result = false;
   return dict->GetBoolean(language, &result) ? result : false;
 }
 
 void TranslatePrefs::ResetDenialState() {
   prefs_->ClearPref(kPrefTranslateLastDeniedTimeForLanguage);
   prefs_->ClearPref(kPrefTranslateTooOftenDeniedForLanguage);
 }
 
-void TranslatePrefs::GetLanguageList(std::vector<std::string>* languages) {
+void TranslatePrefs::GetLanguageList(
+    std::vector<std::string>* languages) const {
   DCHECK(languages);
   DCHECK(languages->empty());
 
 #if defined(OS_CHROMEOS)
   const char* key = preferred_languages_pref_.c_str();
 #else
   const char* key = accept_languages_pref_.c_str();
 #endif
 
   *languages = base::SplitString(prefs_->GetString(key), ",",
@@ skipping 252 matching lines @@
   const base::ListValue* blacklist = prefs_->GetList(pref_id);
   return (blacklist == NULL || blacklist->empty());
 }
 
 bool TranslatePrefs::IsDictionaryEmpty(const char* pref_id) const {
   const base::DictionaryValue* dict = prefs_->GetDictionary(pref_id);
   return (dict == NULL || dict->empty());
 }
 
 }  // namespace translate