The Chromium content layer (which also exposes the NetworkService interface)
generally runs on the UI thread. Previous use of the IO thread for CookieManager
callbacks is an implementation detail of the old network stack that shouldn't be
exposed to clients.
To test: Run ceftests. They should pass as expected.
To test: Run `ceftests --gtest_filter=CookieTest.*:-CookieTest.GetCookieManager*
--enable-network-service`
There should be no functional change when running without the NetworkService
enabled.
Known issues:
- CefCookieManager::SetSupportedSchemes is not yet implemented.
