Add the new UMA key 'Translate.LocalesOnDisabledByPrefs'.

chrome/browser/translate/translate_manager_metrics.h

Index: chrome/browser/translate/translate_manager_metrics.h
diff --git a/chrome/browser/translate/translate_manager_metrics.h b/chrome/browser/translate/translate_manager_metrics.h
index 98ba3503d142aec9b2999c684f0bc6b90f9fe5f8..e0378bc15b3c8c04c84aa0dda3ccc618c403ef18 100644
--- a/chrome/browser/translate/translate_manager_metrics.h
+++ b/chrome/browser/translate/translate_manager_metrics.h
@@ -16,6 +16,7 @@ enum MetricsNameIndex {
   UMA_LANGUAGE_DETECTION_ERROR,
   UMA_SERVER_REPORTED_UNSUPPORTED_LANGUAGE,
   UMA_UNSUPPORTED_LANGUAGE_AT_INITIATION,
+  UMA_LOCALES_ON_DISABLED_BY_PREFS,
   UMA_MAX,
 };
 
@@ -49,6 +50,8 @@ void ReportUnsupportedLanguage();
 
 void ReportUnsupportedLanguageAtInitiation(const std::string& language);
 
+void ReportLocalesOnDisabledByPrefs(const std::string& locale);
+
 // Provides UMA entry names for unit tests.
 const char* GetMetricsName(MetricsNameIndex index);