Get signals working in the EXTRA_DATA section of MHTML

chrome/browser/android/offline_pages/recent_tab_helper.cc

Index: chrome/browser/android/offline_pages/recent_tab_helper.cc
diff --git a/chrome/browser/android/offline_pages/recent_tab_helper.cc b/chrome/browser/android/offline_pages/recent_tab_helper.cc
index 1be59e3e1a62eaca49056769098d98b2ef67ff81..fef6dc1ec6ce33bf476f16c9af9a7a6592cdbdf4 100644
--- a/chrome/browser/android/offline_pages/recent_tab_helper.cc
+++ b/chrome/browser/android/offline_pages/recent_tab_helper.cc
@@ -355,8 +355,10 @@ void RecentTabHelper::ContinueSnapshotAfterPurge(
   save_page_params.client_id = snapshot_info->client_id;
   save_page_params.proposed_offline_id = snapshot_info->request_id;
   save_page_params.is_background = false;
+  std::vector<std::string> signal_data;
   page_model_->SavePage(
       save_page_params, delegate_->CreatePageArchiver(web_contents()),
+      signal_data,
       base::Bind(&RecentTabHelper::SavePageCallback,
                  weak_ptr_factory_.GetWeakPtr(), snapshot_info));
 }