Allow ProxyService to share URLRequestContext with everything else.

net/proxy/proxy_script_fetcher.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.
 
 // ProxyScriptFetcher is an async interface for fetching a proxy auto config
 // script. It is specific to fetching a PAC script; enforces timeout, max-size,
 // status code.
 
 #ifndef NET_PROXY_PROXY_SCRIPT_FETCHER_H_
 #define NET_PROXY_PROXY_SCRIPT_FETCHER_H_
@@ skipping 36 matching lines @@
   virtual int Fetch(const GURL& url,
                     base::string16* utf16_text,
                     const CompletionCallback& callback) = 0;
 
   // Aborts the in-progress fetch (if any).
   virtual void Cancel() = 0;
 
   // Returns the request context that this fetcher uses to issue downloads,
   // or NULL.
   virtual URLRequestContext* GetRequestContext() const = 0;
+
+  // Fails the in-progress fetch (if any) and future requests will fail
+  // immediately. GetRequestContext() will always return nullptr after this is
+  // called.  Must be called before the URLRequestContext the fetcher was
+  // created with is torn down.
+  virtual void OnShutdown() = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_SCRIPT_FETCHER_H_