Remove duplicate application cpp files in mojo/application.

mojo/application/application_test_main_chromium.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 "base/at_exit.h"
-#include "base/command_line.h"
-#include "base/test/test_timeouts.h"
-#include "mojo/application/application_runner_chromium.h"
-#include "mojo/application/application_test_base_chromium.h"
-#include "mojo/public/c/system/main.h"
-
-MojoResult MojoMain(MojoHandle handle) {
-  // An AtExitManager instance is needed to construct message loops.
-  base::AtExitManager at_exit;
-
-  // Initialize the current process Commandline and test timeouts.
-  mojo::ApplicationRunnerChromium::InitBaseCommandLine();
-  TestTimeouts::Initialize();
-
-  return mojo::test::RunAllTests(handle);
-}