Add ScopedTaskEnvironment in extensions::ModuleSystemTest.

extensions/renderer/api_test_base.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 EXTENSIONS_RENDERER_API_TEST_BASE_H_
 #define EXTENSIONS_RENDERER_API_TEST_BASE_H_
 
 #include <map>
 #include <string>
 #include <utility>
 
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "extensions/renderer/module_system_test.h"
 #include "extensions/renderer/v8_schema_registry.h"
 #include "gin/handle.h"
 #include "gin/modules/module_registry.h"
 #include "gin/object_template_builder.h"
 #include "gin/wrappable.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/system/core.h"
 
@@ skipping 86 matching lines @@
   ~ApiTestBase() override;
   void SetUp() override;
   void RunTest(const std::string& file_name, const std::string& test_name);
 
   ApiTestEnvironment* api_test_env() { return test_env_.get(); }
   TestInterfaceProvider* interface_provider() {
     return test_env_->interface_provider();
   }
 
  private:
-  base::MessageLoop message_loop_;
   std::unique_ptr<ApiTestEnvironment> test_env_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_API_TEST_BASE_H_