Cleanup mojo_shell and sample_app a bit

mojo/loader/loader.h

-// Copyright 2013 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_LOADER_LOADER_H_
-#define MOJO_LOADER_LOADER_H_
-
-#include "base/files/file_path.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/single_thread_task_runner.h"
-#include "mojo/loader/job.h"
-#include "url/gurl.h"
-
-namespace mojo {
-namespace loader {
-
-class Loader {
- public:
-  Loader(base::SingleThreadTaskRunner* network_runner,
-         base::SingleThreadTaskRunner* file_runner,
-         base::FilePath base_path);
-  ~Loader();
-
-  scoped_ptr<Job> Load(const GURL& app_url, Job::Delegate* delegate);
-
- private:
-  class Data;
-
-  scoped_ptr<Data> data_;
-
-  DISALLOW_COPY_AND_ASSIGN(Loader);
-};
-
-}  // namespace loader
-}  // namespace mojo
-
-#endif  // MOJO_LOADER_LOADER_H_