Pref service: enable for user prefs in chrome behind a flag.

chrome/browser/profiles/profile_impl.cc

Index: chrome/browser/profiles/profile_impl.cc
diff --git a/chrome/browser/profiles/profile_impl.cc b/chrome/browser/profiles/profile_impl.cc
index 7e58befa635986dbc5b42a85f2275f5fe5e262a0..4c6b495e2a6906955580fc19e44e26a569b43927 100644
--- a/chrome/browser/profiles/profile_impl.cc
+++ b/chrome/browser/profiles/profile_impl.cc
@@ -496,7 +496,7 @@ ProfileImpl::ProfileImpl(
       connector = content::BrowserContext::GetConnectorFor(this);
     }
     prefs_ = chrome_prefs::CreateProfilePrefs(
-        path_, sequenced_task_runner, pref_validation_delegate_.get(),
+        path_, sequenced_task_runner, &pref_validation_delegate_,
         profile_policy_connector_->policy_service(), supervised_user_settings,
         CreateExtensionPrefStore(this, false), pref_registry_, async_prefs,
         connector);
@@ -1070,6 +1070,8 @@ void ProfileImpl::RegisterInProcessServices(StaticServiceMap* services) {
               prefs::PrefStoreManagerImpl::PrefStoreTypes(),
               content::BrowserThread::GetBlockingPool());
         });
+    info.task_runner = content::BrowserThread::GetTaskRunnerForThread(
+        content::BrowserThread::IO);
     services->insert(std::make_pair(prefs::mojom::kPrefStoreServiceName, info));
   }
 }