Don't DCHECK in AttachmentServiceProxyForTest when MessageLoop is absent

sync/internal_api/attachments/attachment_service_proxy_for_test.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/internal_api/public/attachments/attachment_service_proxy_for_test.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/thread_task_runner_handle.h"
 #include "sync/internal_api/public/attachments/attachment_service_impl.h"
 
@@ skipping 20 matching lines @@
   // WeakPtrFactory here and pass it to the ctor so that it may initialize its
   // base class and own the WeakPtrFactory.
   //
   // We must pass by scoped_ptr because WeakPtrFactory has no copy constructor.
   scoped_ptr<base::WeakPtrFactory<AttachmentService> > weak_ptr_factory(
       new base::WeakPtrFactory<AttachmentService>(wrapped.get()));
 
   scoped_refptr<Core> core_for_test(
       new OwningCore(wrapped.Pass(), weak_ptr_factory.Pass()));
 
-  scoped_refptr<base::SequencedTaskRunner> runner(
-      base::ThreadTaskRunnerHandle::Get());
-  if (!runner.get()) {
-    // Dummy runner for tests that don't care about AttachmentServiceProxy.
+  scoped_refptr<base::SequencedTaskRunner> runner;
+  if (base::ThreadTaskRunnerHandle::IsSet()) {
+    runner = base::ThreadTaskRunnerHandle::Get();
+  } else {
+    // Dummy runner for tests that don't have MessageLoop.
     DVLOG(1) << "Creating dummy MessageLoop for AttachmentServiceProxy.";
     base::MessageLoop loop;
     // This works because |runner| takes a ref to the proxy.
-    runner = loop.message_loop_proxy();
+    runner = base::ThreadTaskRunnerHandle::Get();
   }
   return AttachmentServiceProxyForTest(runner, core_for_test);
 }
 
 AttachmentServiceProxyForTest::~AttachmentServiceProxyForTest() {
 }
 
 AttachmentServiceProxyForTest::AttachmentServiceProxyForTest(
     const scoped_refptr<base::SequencedTaskRunner>& wrapped_task_runner,
     const scoped_refptr<Core>& core)
     : AttachmentServiceProxy(wrapped_task_runner, core) {
 }
 
 }  // namespace syncer