I think that question is self-explained :-)
When I browse to Application eclipse send me an error.
In Finder, right click on Google Chrome.app, select Show Package Contents and browse down to Contents/Mac OS and drag Google Chrome to the Location in Eclipse's Edit External Web Browser dialog box. Enter -url %URL% in the field Parameters. This worked for me on Eclipse Indigo on MacOS 10.7, at least when Chrome was not started before...