Add an experimental flag for offlining.

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"
 
 namespace offline_pages {
 
 const base::Feature kOfflineBookmarksFeature {
    "OfflineBookmarks", base::FEATURE_DISABLED_BY_DEFAULT
 };
 
 const base::Feature kOffliningRecentPagesFeature {
    "OfflineRecentPages", base::FEATURE_DISABLED_BY_DEFAULT
 };
 
 const base::Feature kOfflinePagesBackgroundLoadingFeature {
    "OfflinePagesBackgroundLoading", base::FEATURE_DISABLED_BY_DEFAULT
 };
 
+const base::Feature kOfflinePagesCTFeature {
+   "OfflinePagesCT", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
 bool IsOfflinePagesEnabled() {
   return IsOfflineBookmarksEnabled() || IsOffliningRecentPagesEnabled() ||
-         IsOfflinePagesBackgroundLoadingEnabled();
+         IsOfflinePagesBackgroundLoadingEnabled() || IsOfflinePagesCTEnabled();
 }
 
 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);
+}
+
 }  // namespace offline_pages