[net/http auth] Make HttpAuthHandler challenge handling asynchronous.

net/http/proxy_client_socket.h

Index: net/http/proxy_client_socket.h
diff --git a/net/http/proxy_client_socket.h b/net/http/proxy_client_socket.h
index 2d6688f72fd84620ef57784504e264d6c52ab3f5..8f011c7e60517f39952719a576b4b2c30476efc0 100644
--- a/net/http/proxy_client_socket.h
+++ b/net/http/proxy_client_socket.h
@@ -63,12 +63,6 @@ class NET_EXPORT_PRIVATE ProxyClientSocket : public StreamSocket {
                                  std::string* request_line,
                                  HttpRequestHeaders* request_headers);
 
-  // When an auth challenge (407 response) is received during tunnel
-  // construction/ this method should be called.
-  static int HandleProxyAuthChallenge(HttpAuthController* auth,
-                                      HttpResponseInfo* response,
-                                      const BoundNetLog& net_log);
-
   // Logs (to the log and in a histogram) a blocked CONNECT response.
   static void LogBlockedTunnelResponse(int http_response_code,
                                        bool is_https_proxy);