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 f037cfe55d5b5712133a64343e231287697250e3..9ef2d467f09742276558b2099371326ae4201771 100644
--- a/chrome/browser/translate/translate_manager_metrics.h
+++ b/chrome/browser/translate/translate_manager_metrics.h
@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_TRANSLATE_TRANSLATE_MANAGER_METRICS_H_
 #define CHROME_BROWSER_TRANSLATE_TRANSLATE_MANAGER_METRICS_H_
 
+#include <string>
+
 namespace TranslateManagerMetrics {
 
 // An indexing type to query each UMA entry name via GetMetricsName() function.
@@ -13,6 +15,7 @@ enum MetricsNameIndex {
   UMA_INITIATION_STATUS,
   UMA_LANGUAGE_DETECTION_ERROR,
   UMA_SERVER_REPORTED_UNSUPPORTED_LANGUAGE,
+  UMA_LOCALES_ON_DISABLED_BY_PREFS,
   UMA_MAX,
 };
 
@@ -44,6 +47,8 @@ void ReportLanguageDetectionError();
 // Called when it turns out that translating page is in unsupported language.
 void ReportUnsupportedLanguage();
 
+void ReportLocalesOnDisabledByPrefs(const std::string& locale);
+
 // Provides UMA entry names for unit tests.
 const char* GetMetricsName(MetricsNameIndex index);