Fix URLRequestJobFactoryTest::BasicProtocolHandler

Tbr: xunjieli@chromium.org
Change-Id: I8376950bc4120bc8ed3397743fa343d7c849562e
Reviewed-on: https://chromium-review.googlesource.com/1125924
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Eric Noyau <noyau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572556}

net/url_request/url_request_job_factory_impl_unittest.cc

@@ -74,7 +74,8 @@ TEST(URLRequestJobFactoryTest, NoProtocolHandler) {
 }
 
 TEST(URLRequestJobFactoryTest, BasicProtocolHandler) {
-  base::test::ScopedTaskEnvironment scoped_task_environment;
+  base::test::ScopedTaskEnvironment scoped_task_environment(
+      base::test::ScopedTaskEnvironment::MainThreadType::IO);
   TestDelegate delegate;
   URLRequestJobFactoryImpl job_factory;
   TestURLRequestContext request_context;