1 - Create an extension ...
http://code.google.com/chrome/extensions/getstarted.html
2 - Create an NPAPI plugin ...
http://colonelpanic.net/2009/03/building-a-firefox-plugin-part-one/
3 - Add a plugin in the manifest of your extension ...
"plugins": [
{ "path": "your_npapi_plugin.dll" }
],
4 - Create a plugin on the background extension page
<script>
var plugin = document.getElementById("MyNPAPIPluginId");
...
</script>
5 - javascript, script, .
script npapi- , .
MyNPAPIPluginId? , , DLL?
<embed type="application/my-plugin-mimetype" id="MyNPAPIPluginId">
Windows MIMEType DLL,
VALUE "MIMEType", "application/my-plugin-mimetype"