Support needed to measure user and service traffic in Chrome.

components/data_use_measurement/content/data_use_measurement.h

+// Copyright 2015 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_CONTENT_DATA_USE_MEASUREMENT_H_
+#define COMPONENTS_DATA_USE_MEASUREMENT_CONTENT_DATA_USE_MEASUREMENT_H_
+
+#include <stdint.h>
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "build/build_config.h"
+#include "components/data_use_measurement/core/data_use_user_data.h"
+
+#if defined(OS_ANDROID)
+#include "base/android/application_status_listener.h"
+#endif
+
+namespace net {
+class URLRequest;
+}
+
+namespace data_use_measurement {
+
+// Records the data use of user traffic and various services in UMA histograms.
+// The UMA is broken down by network technology used (Wi-Fi vs cellular). On
+// Android, the UMA is further broken down by whether the application was in the
+// background or foreground during the request.
+// TODO(amohammadkhan): Complete the layered architecture.
+// http://crbug.com/527460
+class DataUseMeasurement {
+ public:
+  DataUseMeasurement();
+  ~DataUseMeasurement();
+
+  // Records the data use of the |request|, thus |request| must be non-null.
+  void ReportDataUseUMA(const net::URLRequest* request);

[mmenke, 2015/09/10 15:43:00]

void ReportDataUseUMA(const net::URLRequest* request) const;

[amohammadkhan, 2015/09/10 20:09:00]

Done.

+
+#if defined(OS_ANDROID)
+  // This function should just be used for testing purposes. A change in
+  // application state can be simulated by calling this function.
+  void OnApplicationStateChangeForTesting(
+      base::android::ApplicationState application_state);
+#endif
+
+ private:
+  // Specifies that data is received or sent, respectively.
+  enum TrafficDirection { DOWNSTREAM, UPSTREAM };
+
+  // The state of the application. Only available on Android and on other
+  // platforms it is always FOREGROUND.
+  enum AppState { BACKGROUND, FOREGROUND };
+
+  // The request is from a user or from a service.
+  enum RequestInitiator { REQUEST_INITIATOR_USER, REQUEST_INITIATOR_SERVICE };
+
+  // Returns the current application state (Foreground or Background). It always
+  // returns Foreground if Chrome is not running on Android.
+  AppState CurrentAppState();

[mmenke, 2015/09/10 15:43:00]

AppState CurrentAppState() const;

[amohammadkhan, 2015/09/10 20:09:01]

Done.

+
+  // Produces a string representing whether the data use was on the send
+  // ("Upstream") or receive ("Downstream") path, whether the app was in the
+  // "Foreground" or "Background", and whether a "Cellular" or "WiFi" network
+  // was use. For example, "Upstream.Foreground.Cellular" is a possible output.
+  const std::string GetSuffixForHistogramName(TrafficDirection dir);

[mmenke, 2015/09/10 15:43:00]

The const on the return value doesn't get us anything.  This should be:

std::string GetSuffixForHistogramName(TrafficDirection dir) const;

Note the const on the end.

[amohammadkhan, 2015/09/10 20:09:01]

Done.

+
+#if defined(OS_ANDROID)
+  // Called whenever the application transitions from foreground to background
+  // and vice versa.
+  void OnApplicationStateChange(
+      base::android::ApplicationState application_state);
+#endif
+
+  // A helper function used to record data use of services. It gets the size of
+  // exchanged message, its direction (which is upstream or downstream) and
+  // reports to two histogram groups. DataUse.MessageSize.ServiceName and
+  // DataUse.Services.{Dimensions}. In the second one, services are buckets.
+  void ReportDataUsageServices(
+      data_use_measurement::DataUseUserData::ServiceName service,
+      TrafficDirection dir,
+      int64_t message_size);

[mmenke, 2015/09/10 15:43:00]

int64_t message_size); -> int64_t message_size) const;

[amohammadkhan, 2015/09/10 20:09:01]

Done.

+
+  // A helper function used for reporting data use of user and all the services
+  // as a single group. Two histogram groups are updated by this function. The
+  // first one is DataUse.TrafficSize.User.{Dimensions} and the second one is
+  // DataUse.TrafficSize.System.{Dimensions}. Based on |service_type| one of
+  // these groups is selected and updated.
+  void ReportDataUsageGeneral(RequestInitiator service_type,
+                              TrafficDirection dir,
+                              int64_t message_size);

[mmenke, 2015/09/10 15:43:00]

+const before semi-colon

[amohammadkhan, 2015/09/10 20:09:01]

Done.

+
+#if defined(OS_ANDROID)
+  // Application listener store the last known state of the application in this
+  // field.
+  base::android::ApplicationState app_state_;
+
+  // ApplicationStatusListener used to monitor whether the application is in the
+  // foreground or in the background. It is owned by DataUseMeasurement.
+  scoped_ptr<base::android::ApplicationStatusListener> app_listener_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(DataUseMeasurement);

[mmenke, 2015/09/10 15:43:00]

include base/macros.h for DIASLLOW_COPY_AND_ASSIGN

[amohammadkhan, 2015/09/10 20:09:00]

Done.

+};
+
+}  // namespace data_use_measurement
+
+#endif  // COMPONENTS_DATA_USE_MEASUREMENT_CONTENT_DATA_USE_MEASUREMENT_H_