Adding a previews IO-thread blacklist

chrome/browser/profiles/profile_impl_io_data.cc

Index: chrome/browser/profiles/profile_impl_io_data.cc
diff --git a/chrome/browser/profiles/profile_impl_io_data.cc b/chrome/browser/profiles/profile_impl_io_data.cc
index 9865b76f3cbfddfb260de20402a2009925771087..bc8915693721d310efced2b235118b80dfc7e9b1 100644
--- a/chrome/browser/profiles/profile_impl_io_data.cc
+++ b/chrome/browser/profiles/profile_impl_io_data.cc
@@ -205,21 +205,21 @@ void ProfileImplIOData::Handle::Init(
           profile_->GetRequestContext(), std::move(store),
           BrowserThread::GetTaskRunnerForThread(BrowserThread::UI),
           db_task_runner);
 
   io_data_->set_previews_io_data(base::MakeUnique<previews::PreviewsIOData>(
       BrowserThread::GetTaskRunnerForThread(BrowserThread::UI),
       BrowserThread::GetTaskRunnerForThread(BrowserThread::IO)));
   PreviewsServiceFactory::GetForProfile(profile_)->set_previews_ui_service(
       base::MakeUnique<previews::PreviewsUIService>(
           io_data_->previews_io_data(),
-          BrowserThread::GetTaskRunnerForThread(BrowserThread::IO)));
+          BrowserThread::GetTaskRunnerForThread(BrowserThread::IO), nullptr));
 }
 
 content::ResourceContext*
     ProfileImplIOData::Handle::GetResourceContext() const {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   LazyInitialize();
   return GetResourceContextNoInit();
 }
 
 content::ResourceContext*