Hi,
As you can see, I've done a few combined Firefox and Chrome extensions for clients through this website. I would like to get a few more details about the functionality that you require before putting further effort into bidding; I hope you understand.
Perhaps, you have a specification or project synopsis that you can send me. (I can understand written French reasonably well, so if the document is in that language, it should not be a problem.)
I'm looking forward to hearing from you.