GitLab

If URLRequestContextGetter's refcount drops to zero after the IO thread has
already gone away, the object leaks. This can be tricky to track down, so
now we emit a warning message to the logs.

BUG=142702


Review URL: https://chromiumcodereview.appspot.com/10857008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@151792 0039d316-1c4b-4281-b951-d872f2087c98