Track original URL when downloading a redirected page

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 e7ee1f979c2c3d4737f8d9404f6b5a77c4a483ce..55fbaec6668f2daa91e1938b6e3b9c941b8b86ac 100644
--- a/chrome/browser/android/offline_pages/prerendering_offliner.cc
+++ b/chrome/browser/android/offline_pages/prerendering_offliner.cc
@@ -87,7 +87,9 @@ void PrerenderingOffliner::OnLoadPageDone(
     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())
+    if (!request.original_url().is_empty())
+      save_page_params.original_url = request.original_url();
+    else if (save_page_params.url != request.url())
       save_page_params.original_url = request.url();
 
     SavePage(save_page_params, std::move(archiver),