Get maximum age of clipboard from clipboard_recent_contents.cc in iOS impl

components/open_from_clipboard/clipboard_recent_content.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/open_from_clipboard/clipboard_recent_content.h"
 
 #include "url/url_constants.h"
 
 namespace {
 ClipboardRecentContent* g_clipboard_recent_content = nullptr;
@@ skipping 31 matching lines @@
 bool ClipboardRecentContent::IsAppropriateSuggestion(const GURL& url) {
   // Check to make sure it's a scheme we're willing to suggest.
   for (const auto* authorized_scheme : kAuthorizedSchemes) {
     if (url.SchemeIs(authorized_scheme))
       return true;
   }
 
   // Not a scheme we're allowed to return.
   return false;
 }
+
+// static
+base::TimeDelta ClipboardRecentContent::MaximumAgeOfClipboard() {
+  return base::TimeDelta::FromHours(3);
+}