Record the tab state during data use

components/data_use_measurement/core/data_use_ascriber.h

Index: components/data_use_measurement/core/data_use_ascriber.h
diff --git a/components/data_use_measurement/core/data_use_ascriber.h b/components/data_use_measurement/core/data_use_ascriber.h
index eb591e1cb388968757cd8c4d35b92c002a4ef0d3..067bd34258b720716cab1d5b8275795b31b9eee0 100644
--- a/components/data_use_measurement/core/data_use_ascriber.h
+++ b/components/data_use_measurement/core/data_use_ascriber.h
@@ -43,6 +43,11 @@ class DataUseAscriber {
   virtual DataUseRecorder* GetDataUseRecorder(net::URLRequest* request,
                                               bool can_create_new) = 0;
 
+  // Returns the existing DataUseRecorder to which data usage for the given URL
+  // should be ascribed.
+  virtual const DataUseRecorder* GetDataUseRecorderIfExists(
+      const net::URLRequest* request) const = 0;
+
   // Returns a URLRequestClassifier that can classify requests for metrics
   // recording.
   virtual std::unique_ptr<URLRequestClassifier> CreateURLRequestClassifier()