oSearch: Search via OpenSearch

1. Add OpenSearch Description Document (OSDD) for the site supported, so that the Chrome can recognize that this site exists an search engine.
2. After the page fully loaded, Chrome will add the search engine for this website automatically.
3. All Done! You can simply search the website you want to search by just enter the keyword (usually website address). Then, use a keyboard shortcut which by default is Space or Tab to continue.