There seems to be now a GSoC 2017 category available at [1]. However it seems the Project ideas at the wiki [2] doesn't contain the browser extensions idea for 2017.
Thanks for reply. I saw the list of project ideas on the given page.I need a little advice whether i should post my idea of browser extension or should i chose another project.
Because, I've started working on my idea for creating browser extension and here is the link to my first extension.