[Offlining] Updates the tab helper to use the async OfflinePageModel API

chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc

Index: chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
diff --git a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
index 5c2bcf9e974b81971c14e8a9d0c9ec93545ac6e0..0615896eb51bb702791a00f4a8b5e9b870ab1db0 100644
--- a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
+++ b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
@@ -271,8 +271,9 @@ GURL AddToHomescreenDataFetcher::GetShortcutUrl(const GURL& actual_url) {
       dom_distiller::url_utils::GetOriginalUrlFromDistillerUrl(actual_url);
 
   // If URL points to an offline content, get original URL.
-  GURL online_url = offline_pages::OfflinePageUtils::GetOnlineURLForOfflineURL(
-      web_contents()->GetBrowserContext(), original_url);
+  GURL online_url =
+      offline_pages::OfflinePageUtils::MaybeGetOnlineURLForOfflineURL(
+          web_contents()->GetBrowserContext(), original_url);
   if (online_url.is_valid())
     return online_url;