[Offline pages] Adapting OfflinePageDownloadBridge to DownloadUIAdapter

components/offline_pages/stub_offline_page_model.cc

Index: components/offline_pages/stub_offline_page_model.cc
diff --git a/components/offline_pages/stub_offline_page_model.cc b/components/offline_pages/stub_offline_page_model.cc
index 9d00e46a1993da488bfb75ac168b07b67824762c..9281ea791e12880816b9448b0df2a47146b8e24d 100644
--- a/components/offline_pages/stub_offline_page_model.cc
+++ b/components/offline_pages/stub_offline_page_model.cc
@@ -73,6 +73,9 @@ void StubOfflinePageModel::ExpirePages(
 ClientPolicyController* StubOfflinePageModel::GetPolicyController() {
   return nullptr;
 }
+DownloadUIAdapter* StubOfflinePageModel::GetDownloadUIAdapter() {
+  return nullptr;
+}
 bool StubOfflinePageModel::is_loaded() const {
   return true;
 }