[Offline Pages] Removes two-step expiration related.

components/offline_pages/offline_page_item.cc

Index: components/offline_pages/offline_page_item.cc
diff --git a/components/offline_pages/offline_page_item.cc b/components/offline_pages/offline_page_item.cc
index 0a8a76311b63d1f5a5d044703355b8ed62b0082f..a0f0cc2f1a38304d3a45fc6dc209168a03c8e5e6 100644
--- a/components/offline_pages/offline_page_item.cc
+++ b/components/offline_pages/offline_page_item.cc
@@ -66,15 +66,10 @@ bool OfflinePageItem::operator==(const OfflinePageItem& other) const {
          file_path == other.file_path &&
          creation_time == other.creation_time &&
          last_access_time == other.last_access_time &&
-         expiration_time == other.expiration_time &&
          access_count == other.access_count &&
          title == other.title &&
          flags == other.flags &&
          original_url == other.original_url;
 }
 
-bool OfflinePageItem::IsExpired() const {
-  return creation_time < expiration_time;
-}
-
 }  // namespace offline_pages