Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

chrome/test/base/v8_unit_test.h

Index: chrome/test/base/v8_unit_test.h
diff --git a/chrome/test/base/v8_unit_test.h b/chrome/test/base/v8_unit_test.h
index 2184973937f93d3fcdd5bd6d97b94ee0d0380d6e..c4080763c228aab128c45c5e22b341cbc95c3230 100644
--- a/chrome/test/base/v8_unit_test.h
+++ b/chrome/test/base/v8_unit_test.h
@@ -10,13 +10,10 @@
 
 #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.
@@ -78,6 +75,8 @@ class V8UnitTest : public testing::Test {
   // 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_;
 
@@ -86,8 +85,6 @@ class V8UnitTest : public testing::Test {
 
   // User added libraries.
   std::vector<base::FilePath> user_libraries_;
-
-  std::unique_ptr<base::MessageLoop> loop_;
 };
 
 #endif  // CHROME_TEST_BASE_V8_UNIT_TEST_H_