Cleanup mojo_shell and sample_app a bit

mojo/loader/job.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_JOB_H_
-#define MOJO_LOADER_JOB_H_
-
-#include "url/gurl.h"
-
-namespace base {
-class FilePath;
-}
-
-namespace mojo {
-namespace loader {
-
-// A job represents an individual network load operation.
-class Job {
- public:
-  class Delegate {
-   public:
-    virtual void DidCompleteLoad(const GURL& app_url,
-                                 const base::FilePath& app_path) = 0;
-
-   protected:
-    virtual ~Delegate();
-  };
-
-  // You can cancel a job by deleting it.
-  virtual ~Job();
-
- protected:
-  // You can create a job using Loader.
-  Job();
-
-  DISALLOW_COPY_AND_ASSIGN(Job);
-};
-
-}  // namespace loader
-}  // namespace mojo
-
-#endif  // MOJO_LOADER_JOB_H_