Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

content/public/test/render_view_test.h

Index: content/public/test/render_view_test.h
diff --git a/content/public/test/render_view_test.h b/content/public/test/render_view_test.h
index db2eaef95a9d7f692efa8e02ffe348a7e199e5f3..4665422186e0f5070fab0a63d56945478098758b 100644
--- a/content/public/test/render_view_test.h
+++ b/content/public/test/render_view_test.h
@@ -11,8 +11,8 @@
 #include <string>
 
 #include "base/command_line.h"
-#include "base/message_loop/message_loop.h"
 #include "base/strings/string16.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/test/test_io_thread.h"
 #include "build/build_config.h"
 #include "content/public/browser/native_web_keyboard_event.h"
@@ -190,7 +190,9 @@ class RenderViewTest : public testing::Test, blink::WebLeakDetectorClient {
   // blink::WebLeakDetectorClient implementation.
   void OnLeakDetectionComplete(const Result& result) override;
 
-  base::MessageLoop msg_loop_;
+ protected:
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
+
   std::unique_ptr<FakeCompositorDependencies> compositor_deps_;
   std::unique_ptr<MockRenderProcess> mock_process_;
   // We use a naked pointer because we don't want to expose RenderViewImpl in