Complete the layered architecture of data_use_measurement component.

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/macros.h"
-#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) const;
-
-#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 };
-
-  // Returns the current application state (Foreground or Background). It always
-  // returns Foreground if Chrome is not running on Android.
-  AppState CurrentAppState() const;
-
-  // Makes the full name of the histogram. It is made from |prefix| and suffix
-  // which is made based on network and application status. suffix is 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, "Prefix.Upstream.Foreground.Cellular" is a possible output.
-  std::string GetHistogramName(const char* prefix, TrafficDirection dir) const;
-
-#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) const;
-
-#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);
-};
-
-}  // namespace data_use_measurement
-
-#endif  // COMPONENTS_DATA_USE_MEASUREMENT_CONTENT_DATA_USE_MEASUREMENT_H_