Create a DataUseRecorder instance for each page load in Chrome.

components/data_use_measurement/core/data_use_ascriber.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_DATA_USE_MEASUREMENT_CORE_DATA_USE_ASCRIBER_H_
 #define COMPONENTS_DATA_USE_MEASUREMENT_CORE_DATA_USE_ASCRIBER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 21 matching lines @@
  public:
   virtual ~DataUseAscriber() {}
 
   // Creates a network delegate that will be used to track data use.
   std::unique_ptr<net::NetworkDelegate> CreateNetworkDelegate(
       std::unique_ptr<net::NetworkDelegate> wrapped_network_delegate,
       const metrics::UpdateUsagePrefCallbackType& metrics_data_use_forwarder);
 
   // Returns the DataUseRecorder to which data usage for the given URL should
   // be ascribed. If no existing DataUseRecorder exists, a new one will be
-  // created.
-  virtual DataUseRecorder* GetDataUseRecorder(net::URLRequest* request) = 0;
+  // created only if |can_create_new| is true.
+  virtual DataUseRecorder* GetDataUseRecorder(net::URLRequest* request,
+                                              bool can_create_new) = 0;
+
+  // Returns a URLRequestClassifier that can classify requests for metrics
+  // recording.
+  virtual std::unique_ptr<URLRequestClassifier> CreateURLRequestClassifier()
+      const = 0;
 
   // Methods called by DataUseNetworkDelegate to propagate data use information:
   virtual void OnBeforeUrlRequest(net::URLRequest* request);
-
-  virtual void OnBeforeRedirect(net::URLRequest* request,
-                                const GURL& new_location);
-
   virtual void OnNetworkBytesSent(net::URLRequest* request, int64_t bytes_sent);
-
   virtual void OnNetworkBytesReceived(net::URLRequest* request,
                                       int64_t bytes_received);
-
+  virtual void OnUrlRequestCompleted(net::URLRequest* request, bool started);
   virtual void OnUrlRequestDestroyed(net::URLRequest* request);
-
-  virtual std::unique_ptr<URLRequestClassifier> CreateURLRequestClassifier()
-      const = 0;
 };
 
 }  // namespace data_use_measurement
 
 #endif  // COMPONENTS_DATA_USE_MEASUREMENT_CORE_DATA_USE_ASCRIBER_H_