it was sensed that in Opera the feature/problem isn't switched 'on' by default to give away your location.
But when it is explicitly switched on or "allowed", a random client identifier in Opera is passed along-with other information to Google ! They claim it expires after 2 weeks.
The other options can be checked by typing the below in your Opera browser
Opera may also send IP address, MAC address and signal strength of the nearest access point
If connected to the Internet using a mobile phone tower, it may send cell IDS of the cell tower !
That's a lot of data.
Google+ on the other hand sends out your location in every post you make by default.
Of-course one opt out from it but we are now driving on an Information Freeway
wherein there are way too many checkpoints which one has to explicitly inform to thwart tailing.
The day isn't remotely away when Google or some other yet to be famous browser/company secretly clicks your picture using the front camera of your phone or laptop and uploads it along-with your GPS co-ordinates.
Neo once said :
".. I know you're out there. I can feel you now. I know that you're afraid... you're afraid of us. .. "
Location Tracking companies can conveniently feel like The One, isn't it ?