Add histograms for data usage

chrome/browser/android/data_usage/external_data_use_observer.h

Index: chrome/browser/android/data_usage/external_data_use_observer.h
diff --git a/chrome/browser/android/data_usage/external_data_use_observer.h b/chrome/browser/android/data_usage/external_data_use_observer.h
index ec9c92b00aaeb1b6fa4e79f87594ea7c24ff623e..b1ea76623ab482055bc04364ead74b1a044468dd 100644
--- a/chrome/browser/android/data_usage/external_data_use_observer.h
+++ b/chrome/browser/android/data_usage/external_data_use_observer.h
@@ -82,6 +82,10 @@ class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
   // successfully submitted to the external data use observer by Java.
   void OnReportDataUseDone(bool success);
 
+  // Called by ExternalDataUseObserverBridge when matching rules are fetched
+  // from the Java object.
+  void OnFetchMatchingRulesDone() const;
+
   // Called by DataUseMatcher. |should_register| is true if |this| should
   // register as a data use observer.
   void ShouldRegisterAsDataUseObserver(bool should_register);