[scheduling] Use ScopedTaskEnvironment instead of MessageLoop in web_resource

MessageLoop will go away, eventually.

BUG=891670

Change-Id: I7cb468ba37b76d5765f9941a6101d8115d3f73de
Reviewed-on: https://chromium-review.googlesource.com/c/1352768Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Carlos Caballero <carlscab@google.com>
Cr-Commit-Position: refs/heads/master@{#611715}

components/web_resource/resource_request_allowed_notifier_unittest.cc

@@ -4,8 +4,8 @@
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/web_resource/eula_accepted_notifier.h"
 #include "components/web_resource/resource_request_allowed_notifier_test_util.h"
@@ -119,7 +119,8 @@ class ResourceRequestAllowedNotifierTest
   }
 
  private:
-  base::MessageLoopForUI message_loop_;
+  base::test::ScopedTaskEnvironment task_environment_{
+      base::test::ScopedTaskEnvironment::MainThreadType::UI};
   TestRequestAllowedNotifier resource_request_allowed_notifier_;
   TestingPrefServiceSimple prefs_;
   TestEulaAcceptedNotifier* eula_notifier_;  // Weak, owned by RRAN.

components/web_resource/web_resource_service_unittest.cc

@@ -6,7 +6,7 @@
 #include <utility>
 
 #include "base/bind.h"
-#include "base/message_loop/message_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/values.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
@@ -145,7 +145,7 @@ class WebResourceServiceTest : public testing::Test {
   void CallStartFetch() { test_web_resource_service_->StartFetch(); }
 
  private:
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment task_environment_;
   network::TestURLLoaderFactory test_url_loader_factory_;
   scoped_refptr<network::SharedURLLoaderFactory> test_shared_loader_factory_;
   std::unique_ptr<TestingPrefServiceSimple> local_state_;