[Translate] Factor out access to Accept-Languages

components/translate/core/browser/translate_prefs.cc

Index: components/translate/core/browser/translate_prefs.cc
diff --git a/components/translate/core/browser/translate_prefs.cc b/components/translate/core/browser/translate_prefs.cc
index d02dddebff5796430a65b45d0747232107a4666a..595a8e1bf4c458b6e462b745e47724f019cbb9b2 100644
--- a/components/translate/core/browser/translate_prefs.cc
+++ b/components/translate/core/browser/translate_prefs.cc
@@ -372,6 +372,15 @@ void TranslatePrefs::GetLanguageList(std::vector<std::string>* languages) {
                                  base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 }
 
+void TranslatePrefs::GetAcceptLanguageList(

[groby-ooo-7-16, 2015/12/16 02:48:26]

Since GetAcceptLanguageList is only used by TranslateManager::GetTargetLanguage,
and GetTargetLanguage calls TranslateDownloadManager::GetLanguageCode, I believe
it is safe to just use GetLanguageList, even though it returns the
preferred_languages on ChromeOS. 

I.e. setting the languages to 'en-US', 'ja', 'en-CA' would result in
en-US,ja,en-CA for the preferred languages, 'en-US', 'en', 'ja', 'en-CA' for the
accept-languages. The comparison in GetTargetLanguage calls GetLanguageCode on
all of them, which strips all the en-* variants to en - so the lists are
fundamentally identical.

Please let me know if I misunderstood.

+    std::vector<std::string>* languages) const {
+  DCHECK(languages);
+  DCHECK(languages->empty());
+
+  *languages = base::SplitString(prefs_->GetString(accept_languages_pref_), ",",
+                                 base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+}
+
 void TranslatePrefs::UpdateLanguageList(
     const std::vector<std::string>& languages) {
 #if defined(OS_CHROMEOS)