The cookies are already available via the response headers, this method isn't needed. There's one consumer of this method, URLFetcher, which also makes the headers available to its consumers, and it's calling the method on every successful response needelessly, copying data needlessly when almost no one cares about it.
It looks like there are about 4-5 consumers of URLFetcher's GetResponseCookies method, however, only one of them looks to actually care about the cookies, the rest just ignore them. So all the consumers that don't care can stop calling the method. The one consumer that does care can just grab the response headers, and walk through the cookies itself.
Comment 1 by rdsmith@chromium.org
, Mar 30 2016