Merge to M57: Remove popup overlay from MHTML when requested

chrome/browser/android/offline_pages/prerendering_offliner.cc

Index: chrome/browser/android/offline_pages/prerendering_offliner.cc
diff --git a/chrome/browser/android/offline_pages/prerendering_offliner.cc b/chrome/browser/android/offline_pages/prerendering_offliner.cc
index 6843d2f3b57945d6e0dd29caabd899e0742d9c5b..31c0813bdb86721bd1922114781bf64ee9d8547a 100644
--- a/chrome/browser/android/offline_pages/prerendering_offliner.cc
+++ b/chrome/browser/android/offline_pages/prerendering_offliner.cc
@@ -64,6 +64,7 @@ void PrerenderingOffliner::OnLoadPageDone(
     save_page_params.url = web_contents->GetLastCommittedURL();
     save_page_params.client_id = request.client_id();
     save_page_params.proposed_offline_id = request.request_id();
+    save_page_params.is_background = true;
     // Pass in the original URL if it is different from the last committed URL
     // when redirects occur.
     if (save_page_params.url != request.url())