Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

content/public/test/render_view_test.cc

Index: content/public/test/render_view_test.cc
diff --git a/content/public/test/render_view_test.cc b/content/public/test/render_view_test.cc
index e04ab92c730ea71ff925a9415a3d9207f1aed6e1..1afbb54c36991dd73b3a0f809e619d36c96e67f7 100644
--- a/content/public/test/render_view_test.cc
+++ b/content/public/test/render_view_test.cc
@@ -157,9 +157,7 @@ RenderViewTest::~RenderViewTest() {
 }
 
 void RenderViewTest::ProcessPendingMessages() {

[sky, 2017/05/04 02:58:55]

How about removing this function entirely and having callers use
base::RunLoop().RunUntilIdle() directly?

[fdoray, 2017/05/08 15:22:08]

Done in a separate CL https://codereview.chromium.org/2870633002/

-  msg_loop_.task_runner()->PostTask(FROM_HERE,
-                                    base::MessageLoop::QuitWhenIdleClosure());
-  base::RunLoop().Run();
+  base::RunLoop().RunUntilIdle();
 }
 
 WebLocalFrame* RenderViewTest::GetMainFrame() {