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..21c9d781a1680afbfc80cd5c0e742f2691076fda 100644
--- a/ios/chrome/browser/translate/translate_ranker_metrics_provider.h
+++ b/ios/chrome/browser/translate/translate_ranker_metrics_provider.h
@@ -12,13 +12,21 @@ namespace translate {
 // Provides metrics related to the translate ranker.
 class TranslateRankerMetricsProvider : public metrics::MetricsProvider {
  public:
-  TranslateRankerMetricsProvider() {}
+  TranslateRankerMetricsProvider() : logging_enabled_(false) {}
   ~TranslateRankerMetricsProvider() override {}
 
- private:
   // From metrics::MetricsProvider...
   void ProvideGeneralMetrics(
       metrics::ChromeUserMetricsExtension* uma_proto) override;
+  void OnRecordingEnabled() override;
+  void OnRecordingDisabled() override;
+
+ private:
+  // Updates the logging state of all ranker instances.
+  void UpdateLoggingState();
+
+  // The current state of logging.
+  bool logging_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(TranslateRankerMetricsProvider);
 };