Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

chrome/test/base/v8_unit_test.h

 // Copyright (c) 2011 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 CHROME_TEST_BASE_V8_UNIT_TEST_H_
 #define CHROME_TEST_BASE_V8_UNIT_TEST_H_
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/strings/string_piece.h"
+#include "base/test/scoped_task_environment.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "v8/include/v8.h"
 
-namespace base {
-class MessageLoop;
-}  // namespace base
-
 // A superclass for unit tests that involve running JavaScript.  This class
 // sets up V8 context and has methods that make it easy to execute scripts in
 // this context as well as call functions in the context.
 class V8UnitTest : public testing::Test {
  public:
   V8UnitTest();
   ~V8UnitTest() override;
 
   // Methods from testing::Test.
   void SetUp() override;
@@ skipping 41 matching lines @@
   // capture and hold the results for analysis by |RunJavascriptF|.
   static void ChromeSend(const v8::FunctionCallbackInfo<v8::Value>& args);
 
  private:
   // Executes all added javascript libraries. Returns true if no errors.
   bool ExecuteJavascriptLibraries();
 
   // Initializes paths and libraries.
   void InitPathsAndLibraries();
 
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
+
   // Handle scope that is used throughout the life of this class.
   v8::HandleScope handle_scope_;
 
   // Context for the JavaScript in the test.
   v8::Persistent<v8::Context> context_;
 
   // User added libraries.
   std::vector<base::FilePath> user_libraries_;
-
-  std::unique_ptr<base::MessageLoop> loop_;
 };
 
 #endif  // CHROME_TEST_BASE_V8_UNIT_TEST_H_