Extract some stuff into PackageManager

mojo/shell/application_fetcher.h

-// 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.
-
-#ifndef MOJO_SHELL_APPLICATION_FETCHER_H_
-#define MOJO_SHELL_APPLICATION_FETCHER_H_
-
-#include "mojo/shell/fetcher.h"
-#include "mojo/services/network/public/interfaces/url_loader.mojom.h"
-
-class GURL;
-
-namespace mojo {
-namespace shell {
-
-class ApplicationManager;
-
-// A class implementing this interface assists Shell::ConnectToApplication in
-// resolving URLs and fetching the applications located therein.
-class ApplicationFetcher {
- public:
-  virtual ~ApplicationFetcher() {}
-
-  // Called once, during initialization, to tell the fetcher about the
-  // associated ApplicationManager.
-  virtual void SetApplicationManager(ApplicationManager* manager) = 0;
-
-  // Resolves |url| to its canonical form. e.g. for mojo: urls, returns a file:
-  // url with a path ending in .mojo.
-  virtual GURL ResolveURL(const GURL& url) = 0;
-
-  // Asks the delegate to fetch the specified url. |url| must be unresolved,
-  // i.e. ResolveURL() above must not have been called on it.
-  // TODO(beng): figure out how not to expose Fetcher at all at this layer.
-  virtual void FetchRequest(
-      URLRequestPtr request,
-      const Fetcher::FetchCallback& loader_callback) = 0;
-};
-
-}  // namespace shell
-}  // namespace mojo
-
-#endif  // MOJO_SHELL_APPLICATION_FETCHER_H_