Add "Show saved copy" button in dino page when there's offline copy

components/error_page/common/offline_page_types.h

Index: components/error_page/common/offline_page_types.h
diff --git a/components/error_page/common/offline_page_types.h b/components/error_page/common/offline_page_types.h
new file mode 100644
index 0000000000000000000000000000000000000000..ce027b40c1a7309ed069117473c75a1278f68436
--- /dev/null
+++ b/components/error_page/common/offline_page_types.h
@@ -0,0 +1,24 @@
+// 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.
+
+#ifndef COMPONENTS_ERROR_PAGE_COMMON_OFFLINE_PAGE_TYPES_H_
+#define COMPONENTS_ERROR_PAGE_COMMON_OFFLINE_PAGE_TYPES_H_
+
+namespace error_page {
+
+enum class OfflinePageStatus {
+  // No offline page exists.
+  NONE,
+  // An offline copy of current page exists.
+  HAS_OFFLINE_PAGE,
+  // An offline copy of current page does not exist, but the offline copies of
+  // other pages exist.
+  HAS_OTHER_OFFLINE_PAGES,
+
+  OFFLINE_PAGE_STATUS_LAST = HAS_OTHER_OFFLINE_PAGES,
+};
+
+}  // namespace error_page
+
+#endif  // COMPONENTS_ERROR_PAGE_COMMON_OFFLINE_PAGE_TYPES_H_