Language.{h,cpp} clean-up.

Source/platform/Language.h

Index: Source/platform/Language.h
diff --git a/Source/platform/Language.h b/Source/platform/Language.h
index 56624bbc57ce230fecea9094bc67b5b243407d15..dddc7d812eb61b8024b8f0b7977cce78e2bca4bd 100644
--- a/Source/platform/Language.h
+++ b/Source/platform/Language.h
@@ -32,9 +32,13 @@
 
 namespace blink {
 
+// Returns lowercased BCP-47 language tag such as "en-us".  This is the UI
+// locale of the browser application.
 PLATFORM_EXPORT AtomicString defaultLanguage();
+// Returns a list of lowercased BCP-47 language tags.  This never returns
+// multiple values in production.  This is not a value of Accept-Languages
+// header.  See ChromeClient::acceptLanguages.
 PLATFORM_EXPORT Vector<AtomicString> userPreferredLanguages();
-PLATFORM_EXPORT Vector<AtomicString> userPreferredLanguagesOverride();
 PLATFORM_EXPORT void overrideUserPreferredLanguages(const Vector<AtomicString>&);
 PLATFORM_EXPORT size_t indexOfBestMatchingLanguageInList(const AtomicString& language, const Vector<AtomicString>& languageList);