Add the first app_shell_browsertest test.

apps/test/apps_tests_main.cc

-// 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.
-
-#include <algorithm>
-
-#include "apps/test/apps_test_launcher_delegate.h"
-#include "base/sys_info.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-int main(int argc, char** argv) {
-  int default_jobs = std::max(1, base::SysInfo::NumberOfProcessors() / 2);
-  apps::AppsTestLauncherDelegate launcher_delegate;
-  return content::LaunchTests(&launcher_delegate, default_jobs, argc, argv);
-}