Add timestamp to infobar for stale Previews

components/previews/core/previews_features.cc

Index: components/previews/core/previews_features.cc
diff --git a/components/previews/core/previews_features.cc b/components/previews/core/previews_features.cc
index d88577c41f2415d67e33df414fab4161aa8ab400..00bbedf2c0a7b3ba02857a96f7c715913276f867 100644
--- a/components/previews/core/previews_features.cc
+++ b/components/previews/core/previews_features.cc
@@ -15,5 +15,9 @@ const base::Feature kOfflinePreviews{"OfflinePreviews",
 const base::Feature kClientLoFi{"ClientLoFi",
                                 base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables the Stale Previews timestamp on Previews infobars.
+const base::Feature kStalePreviewsTimestamp{"StalePreviewsTimestamp",
+                                            base::FEATURE_DISABLED_BY_DEFAULT};
+
 }  // namespace features
 }  // namespace previews