ChromeOS: Per-user time zone: refactor tests first.

chrome/browser/chromeos/login/users/chrome_user_manager_impl.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 "chrome/browser/chromeos/login/users/chrome_user_manager_impl.h"
 
 #include <stddef.h>
 
 #include <cstddef>
 #include <set>
@@ skipping 160 matching lines @@
   enterprise_user_session_metrics::RegisterPrefs(registry);
 }
 
 // static
 std::unique_ptr<ChromeUserManager>
 ChromeUserManagerImpl::CreateChromeUserManager() {
   return std::unique_ptr<ChromeUserManager>(new ChromeUserManagerImpl());
 }
 
 ChromeUserManagerImpl::ChromeUserManagerImpl()
-    : ChromeUserManager(base::ThreadTaskRunnerHandle::Get()),
+    : ChromeUserManager(base::ThreadTaskRunnerHandle::IsSet()
+                            ? base::ThreadTaskRunnerHandle::Get()
+                            : scoped_refptr<base::TaskRunner>()),
       cros_settings_(CrosSettings::Get()),
       device_local_account_policy_service_(NULL),
       supervised_user_manager_(new SupervisedUserManagerImpl(this)),
       bootstrap_manager_(new BootstrapManager(this)),
       weak_factory_(this) {
   UpdateNumberOfUsers();
 
   // UserManager instance should be used only on UI thread.
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  // (or in unit tests)
+  if (base::ThreadTaskRunnerHandle::IsSet())
+    DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
   registrar_.Add(this,
                  chrome::NOTIFICATION_OWNERSHIP_STATUS_CHANGED,
                  content::NotificationService::AllSources());
   registrar_.Add(this,
                  chrome::NOTIFICATION_LOGIN_USER_PROFILE_PREPARED,
                  content::NotificationService::AllSources());
   registrar_.Add(this,
                  chrome::NOTIFICATION_PROFILE_CREATED,
                  content::NotificationService::AllSources());
 
@@ skipping 1179 matching lines @@
       break;
     default:
       NOTREACHED();
       break;
   }
 
   return user;
 }
 
 }  // namespace chromeos