Here's a quick tip if you'd like to add Chrome as your default browser (or secondary for that matter) in Flash Builder.
You may have noticed that Eclipse seems to struggle with this if you browse for the location and end up with '/Applications/Google Chrome.app' as the path: it gets rejected as soon as you click 'ok' stating that 'The location value is not a valid path name'.
After a bit of trial and error I managed to find a valid path name after checking out the existing browsers' paths in more detail. Here's what seems to work for me:
/Applications/Google Chrome.app/Contents/MacOS/Google Chrome
Note that under Windows you may not encounter this issue. Hope this helps someone.