Use a new flag to control showing "DOWNLOAD PAGE LATER" in error pages

components/offline_pages/offline_page_feature.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/offline_pages/offline_page_feature.h"
 
 #include <string>
 
 #include "base/feature_list.h"
 
@@ skipping 14 matching lines @@
 const base::Feature kOfflinePagesCTFeature {
    "OfflinePagesCT", base::FEATURE_ENABLED_BY_DEFAULT
 };
 
 const base::Feature kOfflinePagesSharingFeature{
     "OfflinePagesSharing", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kBackgroundLoaderForDownloadsFeature{
     "BackgroundLoadingForDownloads", base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kOfflinePagesAsyncDownloadFeature {
+   "OfflinePagesAsyncDownload", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
 bool IsOfflineBookmarksEnabled() {
   return base::FeatureList::IsEnabled(kOfflineBookmarksFeature);
 }
 
 bool IsOffliningRecentPagesEnabled() {
   return  base::FeatureList::IsEnabled(kOffliningRecentPagesFeature);
 }
 
 bool IsOfflinePagesBackgroundLoadingEnabled() {
   return base::FeatureList::IsEnabled(kOfflinePagesBackgroundLoadingFeature);
 }
 
 bool IsOfflinePagesCTEnabled() {
   return base::FeatureList::IsEnabled(kOfflinePagesCTFeature);
 }
 
 bool IsOfflinePagesSharingEnabled() {
   return base::FeatureList::IsEnabled(kOfflinePagesSharingFeature);
 }
 
 bool IsBackgroundLoaderForDownloadsEnabled() {
   return base::FeatureList::IsEnabled(kBackgroundLoaderForDownloadsFeature);
 }
 
+bool IsOfflinePagesAsyncDownloadEnabled() {
+  return base::FeatureList::IsEnabled(kOfflinePagesAsyncDownloadFeature);
+}
+
 }  // namespace offline_pages