Add the first app_shell_browsertest test.

apps/test/app_shell_test.h

-// Copyright 2014 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 APPS_TEST_APP_SHELL_TEST_H_
-#define APPS_TEST_APP_SHELL_TEST_H_
-
-#include "base/memory/scoped_ptr.h"
-#include "content/public/test/browser_test.h"
-#include "content/public/test/browser_test_base.h"
-
-namespace base {
-class FilePath;
-}
-
-namespace content {
-class BrowserContext;
-}
-
-namespace extensions {
-class ShellExtensionSystem;
-}
-
-namespace apps {
-
-// Base class for app shell browser tests.
-class AppShellTest : public content::BrowserTestBase {
- public:
-  AppShellTest();
-  virtual ~AppShellTest();
-
-  virtual void SetUpOnMainThread() OVERRIDE;
-  virtual void RunTestOnMainThreadLoop() OVERRIDE;
-
-  // Loads an unpacked application from a directory using |extension_system_|
-  // and attempts to launch it. Returns true on success.
-  bool LoadAndLaunchApp(const base::FilePath& app_dir);
-
-  content::BrowserContext* browser_context() { return browser_context_; }
-
- private:
-  content::BrowserContext* browser_context_;
-  extensions::ShellExtensionSystem* extension_system_;
-};
-
-}  // namespace apps
-
-#endif  // APPS_TEST_APP_SHELL_TEST_H_