Allow ProxyService to share URLRequestContext with everything else.

net/proxy/proxy_script_fetcher.h

Index: net/proxy/proxy_script_fetcher.h
diff --git a/net/proxy/proxy_script_fetcher.h b/net/proxy/proxy_script_fetcher.h
index ed89268352f22a316c64b0259609556391ae8a9a..3905b100babfaf7c9bb4c7e183ad1a37a9f08e4b 100644
--- a/net/proxy/proxy_script_fetcher.h
+++ b/net/proxy/proxy_script_fetcher.h
@@ -54,6 +54,12 @@ class NET_EXPORT_PRIVATE ProxyScriptFetcher {
   // 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