[Android WebView] Implement support for Network Information API and enable it.

android_webview/browser/net/aw_network_change_notifier.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 ANDROID_WEBVIEW_BROWSER_NET_AW_NETWORK_CHANGE_NOTIFIER_H_
+#define ANDROID_WEBVIEW_BROWSER_NET_AW_NETWORK_CHANGE_NOTIFIER_H_
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "net/android/network_change_notifier_delegate_android.h"
+#include "net/base/network_change_notifier.h"
+
+namespace android_webview {
+
+// AwNetworkChangeNotifier is similar to NetworkChangeNotifierAndroid except
+// it only propagates max-bandwidth changes in order to make the Network
+// Information API work in blink.
+//
+// This somewhat reduced functionality is necessary because of the way
+// NetworkChangeNotifier is enabled in WebView. It is enabled only when there
+// are living WebView instances (instead of using ApplicationStatus) hence the
+// existing Chrome for Android implementation is not applicable as is
+// (see crbug.com/529434).
+class AwNetworkChangeNotifier
+    : public net::NetworkChangeNotifier,
+      public net::NetworkChangeNotifierDelegateAndroid::Observer {
+ public:
+  ~AwNetworkChangeNotifier() override;
+
+  // NetworkChangeNotifier:
+  ConnectionType GetCurrentConnectionType() const override;
+  // Requires ACCESS_WIFI_STATE permission in order to provide precise WiFi link
+  // speed.
+  void GetCurrentMaxBandwidthAndConnectionType(
+      double* max_bandwidth_mbps,
+      ConnectionType* connection_type) const override;
+  bool AreNetworkHandlesCurrentlySupported() const override;
+  void GetCurrentConnectedNetworks(NetworkList* network_list) const override;
+  ConnectionType GetCurrentNetworkConnectionType(
+      NetworkHandle network) const override;
+  NetworkHandle GetCurrentDefaultNetwork() const override;
+
+  // NetworkChangeNotifierDelegateAndroid::Observer:
+  void OnConnectionTypeChanged() override;
+  void OnMaxBandwidthChanged(double max_bandwidth_mbps,
+                             ConnectionType type) override;
+  void OnNetworkConnected(NetworkHandle network) override;
+  void OnNetworkSoonToDisconnect(NetworkHandle network) override;
+  void OnNetworkDisconnected(NetworkHandle network) override;
+  void OnNetworkMadeDefault(NetworkHandle network) override;
+
+ private:
+  friend class AwNetworkChangeNotifierFactory;
+
+  AwNetworkChangeNotifier(net::NetworkChangeNotifierDelegateAndroid* delegate);
+
+  static NetworkChangeCalculatorParams DefaultNetworkChangeCalculatorParams();
+
+  net::NetworkChangeNotifierDelegateAndroid* const delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(AwNetworkChangeNotifier);
+};
+
+}  // namespace android_webview
+
+#endif  // ANDROID_WEBVIEW_BROWSER_NET_AW_NETWORK_CHANGE_NOTIFIER_H_