Get signals working in the EXTRA_DATA section of MHTML

chrome/browser/android/offline_pages/background_loader_offliner.cc

Index: chrome/browser/android/offline_pages/background_loader_offliner.cc
diff --git a/chrome/browser/android/offline_pages/background_loader_offliner.cc b/chrome/browser/android/offline_pages/background_loader_offliner.cc
index 07b32f956610f7021e66e5f8d32a9027f553c854..d3f766048b42ad62cbd1bf6cd5bb51cf7b896333 100644
--- a/chrome/browser/android/offline_pages/background_loader_offliner.cc
+++ b/chrome/browser/android/offline_pages/background_loader_offliner.cc
@@ -300,8 +300,11 @@ void BackgroundLoaderOffliner::SavePage() {
   else if (params.url != request.url())
     params.original_url = request.url();
 
+  // TODO(petewil): Generate signal data.  Blank for now.
+  std::string signal_data;
+
   offline_page_model_->SavePage(
-      params, std::move(archiver),
+      params, std::move(archiver), signal_data,
       base::Bind(&BackgroundLoaderOffliner::OnPageSaved,
                  weak_ptr_factory_.GetWeakPtr()));
 }