Add an experimental flag for offlining.

components/offline_pages/offline_page_feature.cc

Index: components/offline_pages/offline_page_feature.cc
diff --git a/components/offline_pages/offline_page_feature.cc b/components/offline_pages/offline_page_feature.cc
index 159ea9a862f6db89d208778a5a52178b0940b372..d522bc9658639475d71ae50fa7352eb223f3c2f7 100644
--- a/components/offline_pages/offline_page_feature.cc
+++ b/components/offline_pages/offline_page_feature.cc
@@ -22,9 +22,13 @@ 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() {
@@ -39,4 +43,8 @@ bool IsOfflinePagesBackgroundLoadingEnabled() {
   return base::FeatureList::IsEnabled(kOfflinePagesBackgroundLoadingFeature);
 }
 
+bool IsOfflinePagesCTEnabled() {
+  return base::FeatureList::IsEnabled(kOfflinePagesCTFeature);
+}
+
 }  // namespace offline_pages