Yes, you will have legal troubles.
Google do not allow their trademarks in domain names. They say so quite clearly in their terms and conditions to not do it.
You will be hearing from their lawyers when/if they find you using it - its up to you if you want to take the risk of them not seeing it.
You may get away with it, but at any stage they can demand that the domain name be handed over to them and there will be nothing you can do and all that effort of creating and promoting the site will be lost.