Remove duplicate application cpp files in mojo/application.

mojo/application/application_test_base_chromium.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 MOJO_APPLICATION_APPLICATION_TEST_BASE_CHROMIUM_H_
-#define MOJO_APPLICATION_APPLICATION_TEST_BASE_CHROMIUM_H_
-
-#include "mojo/application/public/cpp/application_delegate.h"
-#include "mojo/application/public/interfaces/application.mojom.h"
-#include "mojo/public/cpp/bindings/array.h"
-#include "mojo/public/cpp/bindings/string.h"
-#include "mojo/public/cpp/system/macros.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace mojo {
-
-class ApplicationImpl;
-
-namespace test {
-
-// Run all application tests. This must be called after the environment is
-// initialized, to support construction of a default run loop.
-MojoResult RunAllTests(MojoHandle application_request_handle);
-
-// A GTEST base class for application testing executed in mojo_shell.
-class ApplicationTestBase : public testing::Test {
- public:
-  ApplicationTestBase();
-  ~ApplicationTestBase() override;
-
- protected:
-  ApplicationImpl* application_impl() { return application_impl_; }
-
-  // Get the ApplicationDelegate for the application to be tested.
-  virtual ApplicationDelegate* GetApplicationDelegate();
-
-  // testing::Test:
-  void SetUp() override;
-  void TearDown() override;
-
-  // True by default, which indicates a MessageLoop will automatically be
-  // created for the application.  Tests may override this function to prevent
-  // a default loop from being created.
-  virtual bool ShouldCreateDefaultRunLoop();
-
- private:
-  // The application implementation instance, reconstructed for each test.
-  ApplicationImpl* application_impl_;
-  // The application delegate used if GetApplicationDelegate is not overridden.
-  ApplicationDelegate default_application_delegate_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(ApplicationTestBase);
-};
-
-}  // namespace test
-
-}  // namespace mojo
-
-#endif  // MOJO_APPLICATION_APPLICATION_TEST_BASE_CHROMIUM_H_