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

chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc

Index: chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
diff --git a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
index 495331f77b2a7ea4ab99465d94ccab25fec5975a..07c7c7d6378174527e0785a52eb5cd634aef19ae 100644
--- a/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/users/chrome_user_manager_impl.cc
@@ -194,7 +194,9 @@ ChromeUserManagerImpl::CreateChromeUserManager() {
 }
 
 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)),
@@ -203,7 +205,10 @@ ChromeUserManagerImpl::ChromeUserManagerImpl()
   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());