I find it ironic that a “protection” software package like Avast would try to auto-install from a compant as vile as google. They willingly distribute private information. I pay attention to programs that do this, if it happens again I’m going to find another anti-virus. This may seem like I’m complaining about nothing, but it’s a matter of principle.
You say “I pay attention to programs that do this” how did you install avast 8 ?
As it is indicated on the first Configuration screen in the installation (see image) about chrome, did you see that ?
Sorry to say but this is an ever increasing marketing ploy/tool.
I wish they were all opt-in and not opt-out. Anymore when installing any software the user must be extra cautious
to prevent unwanted software from being installed.
I am not backing up Google but all search engines, Yahoo, Bing, Ask among others, use every search as a marketing tool.
Each time you do a search someone somewhere is using that information to target advertising to you and whoever else
is using their search engine. Companies are more than willing to “pay per click” to sell their products and/or services.
There is nothing new here. There are some very specific guidelines in how that personal information is used. 
avast does “not” sell, trade or distribute your personal information. 8)