Componentize proxy code from chrome/browser/net

chrome/browser/net/pref_proxy_config_tracker.h

-// Copyright (c) 2011 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_PREF_PROXY_CONFIG_TRACKER_H_
-#define CHROME_BROWSER_NET_PREF_PROXY_CONFIG_TRACKER_H_
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-
-namespace net {
-class ProxyConfigService;
-}
-
-// Interface for a class that tracks proxy preferences. The purpose of the
-// concrete class is to track changes in the Preferences, to translates the
-// preferences to net::ProxyConfig and to push the result over to a
-// net::ProxyConfigService onto the IO thread.
-class PrefProxyConfigTracker {
- public:
-  PrefProxyConfigTracker();
-  virtual ~PrefProxyConfigTracker();
-
-  // Creates a net::ProxyConfigService and keeps a pointer to it. After this
-  // call, this tracker forwards any changes of proxy preferences to the created
-  // ProxyConfigService. The returned ProxyConfigService must not be deleted
-  // before DetachFromPrefService was called. Takes ownership of the passed
-  // |base_service|, which can be NULL. This |base_service| provides the proxy
-  // settings of the OS (except of ChromeOS). This must be called on the
-  // UI thread.
-  virtual scoped_ptr<net::ProxyConfigService> CreateTrackingProxyConfigService(
-      scoped_ptr<net::ProxyConfigService> base_service) = 0;
-
-  // Releases the PrefService passed upon construction and the |base_service|
-  // passed to CreateTrackingProxyConfigService. This must be called on the UI
-  // thread.
-  virtual void DetachFromPrefService() = 0;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(PrefProxyConfigTracker);
-};
-
-#endif  // CHROME_BROWSER_NET_PREF_PROXY_CONFIG_TRACKER_H_