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

components/open_from_clipboard/clipboard_recent_content.h

Index: components/open_from_clipboard/clipboard_recent_content.h
diff --git a/components/open_from_clipboard/clipboard_recent_content.h b/components/open_from_clipboard/clipboard_recent_content.h
index 93e9a50ff08e4c644d3ec075160f496efe1bf988..78a1b49c4bff4965019abee2ab5733234f42aa75 100644
--- a/components/open_from_clipboard/clipboard_recent_content.h
+++ b/components/open_from_clipboard/clipboard_recent_content.h
@@ -43,7 +43,7 @@ class ClipboardRecentContent {
  protected:
   // GetRecentURLFromClipboard() should never return a URL from a clipboard
   // older than this.
-  const base::TimeDelta kMaximumAgeOfClipboard = base::TimeDelta::FromHours(3);
+  static base::TimeDelta MaximumAgeOfClipboard();
 
   // Returns true if the URL is appropriate to be suggested.
   static bool IsAppropriateSuggestion(const GURL& url);