Respect QuicAllowed policy for new streams

chrome/browser/net/net_pref_observer.h

+// Copyright (c) 2012 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 CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
+#define CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
+
+#include "base/macros.h"
+#include "components/prefs/pref_member.h"
+
+class PrefService;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+class IOThread;
+
+// Monitors network-related preferences for changes and applies them to
+// globally owned HttpNetworkSessions.
+// Profile-owned HttpNetworkSessions are taken care of by a
+// UpdateNetParamsCallback passed to the constructor.
+// The supplied PrefService must outlive this NetPrefObserver.
+// Must be used only on the UI thread.
+class NetPrefObserver {
+ public:
+  // Describes what change in terms of net parameters.
+  struct NetParamsChange {
+    // New value of QUIC enablement.
+    bool quic_enabled_new;
+  };
+
+  // Type of callback which will be called when enablement of QUIC is changed.
+  // This callback will be called on the UI thread.
+  typedef base::Callback<void(NetParamsChange)> UpdateNetParamsCallback;
+
+  // |prefs| must be non-NULL and |*prefs| must outlive this.
+  // |update_net_params_callback| will be invoked on the IO thread when an
+  // observed network parmeter is changed.
+  NetPrefObserver(PrefService* prefs,
+                  UpdateNetParamsCallback update_net_params_callback);
+  ~NetPrefObserver();
+
+  // Register user preferences which NetPrefObserver uses into |registry|.
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
+ private:
+  // Called on UI thread when an observed net pref changes
+  void ApplySettings();
+
+  // Called on IO thread from ApplySettings
+  void ApplySettingsOnIOThread(IOThread* io_thread,
+                               NetParamsChange net_params_change);
+
+  BooleanPrefMember quic_allowed_;
+  UpdateNetParamsCallback update_net_params_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetPrefObserver);
+};
+
+#endif  // CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_