Change AuthenticatingURLLoader to be a URLLoaderInterceptor

shell/authenticating_url_loader_loader.cc

-// Copyright 2015 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.
-
-#include "base/logging.h"
-#include "shell/authenticating_url_loader_loader.h"
-
-namespace shell {
-
-AuthenticatingURLLoaderLoader::AuthenticatingURLLoaderLoader() {
-}
-
-AuthenticatingURLLoaderLoader::~AuthenticatingURLLoaderLoader() {
-}
-
-void AuthenticatingURLLoaderLoader::Load(
-    const GURL& url,
-    mojo::InterfaceRequest<mojo::Application> application_request) {
-  DCHECK(application_request.is_pending());
-  application_.reset(new mojo::ApplicationImpl(&authenticating_url_loader_,
-                                               application_request.Pass()));
-}
-
-}  // namespace shell