Send UMA recording state to TranslateRanker.

ios/chrome/browser/translate/translate_ranker_metrics_provider.h

Index: ios/chrome/browser/translate/translate_ranker_metrics_provider.h
diff --git a/ios/chrome/browser/translate/translate_ranker_metrics_provider.h b/ios/chrome/browser/translate/translate_ranker_metrics_provider.h
index 1933a4b3b6b64839b97b09b23f0b7a3e876ec45c..b376cc307cf829094861d826617520e359228a5c 100644
--- a/ios/chrome/browser/translate/translate_ranker_metrics_provider.h
+++ b/ios/chrome/browser/translate/translate_ranker_metrics_provider.h
@@ -15,10 +15,15 @@ class TranslateRankerMetricsProvider : public metrics::MetricsProvider {
   TranslateRankerMetricsProvider() {}
   ~TranslateRankerMetricsProvider() override {}
 
- private:
   // From metrics::MetricsProvider...
   void ProvideGeneralMetrics(
       metrics::ChromeUserMetricsExtension* uma_proto) override;
+  void OnRecordingEnabled() override;
+  void OnRecordingDisabled() override;
+
+ private:
+  // Enables or disables the logging for translate ranker.
+  void SetLoggingState(bool logging_enabled);
 
   DISALLOW_COPY_AND_ASSIGN(TranslateRankerMetricsProvider);
 };