Notify NQE of TCP RTT values

net/base/network_quality_estimator_watcher_factory.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 NET_BASE_NETWORK_QUALITY_ESTIMATOR_WATCHER_FACTORY_H_
+#define NET_BASE_NETWORK_QUALITY_ESTIMATOR_WATCHER_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "net/base/net_export.h"
+#include "net/base/socket_performance_watcher.h"
+#include "net/base/socket_performance_watcher_factory.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+class TimeDelta;
+}
+
+namespace net {
+
+class NetworkQualityEstimator;
+
+// NetworkQualityEstimatorWatcherFactory implements
+// SocketPerformanceWatcherFactory, and is owned by |NetworkQualityEstimator|.
+// |NetworkQualityEstimatorWatcherFactory| is thread safe.
+class NET_EXPORT_PRIVATE NetworkQualityEstimatorWatcherFactory

[Ryan Sleevi, 2016/03/25 01:45:34]

Why is this a separate class? That is, why isn't it a helper scoped solely to
the implementation of the NQE?

+    : public SocketPerformanceWatcherFactory {
+ public:
+  // |network_quality_estimator| owns |this|, and is notified on |task_runner|
+  // every time |this| receives a notification from |SocketPerformanceWatcher|.
+  NetworkQualityEstimatorWatcherFactory(
+      const base::WeakPtr<NetworkQualityEstimator>& network_quality_estimator,
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+
+  ~NetworkQualityEstimatorWatcherFactory() override;
+
+  // SocketPerformanceWatcherFactory implementation:
+  scoped_ptr<SocketPerformanceWatcher> CreateSocketPerformanceWatcher(
+      const Protocol protocol) override;
+  void OnUpdatedRTTAvailable(const Protocol protocol,
+                             const base::TimeDelta& rtt) override;
+  void OnWatcherReset() override;
+
+ private:
+  // Guaranteed to be non-null since |network_quality_estimator_| owns |this|.
+  base::WeakPtr<NetworkQualityEstimator> network_quality_estimator_;
+
+  // TaskRunner on which |network_quality_estimator_| should be notified.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimatorWatcherFactory);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_NETWORK_QUALITY_ESTIMATOR_WATCHER_FACTORY_H_