Use IsStreamError() and friends gMock matchers in quic/core (but not subdirectories).
gfe-relnote: n/a, test-only change.
PiperOrigin-RevId: 282792467
Change-Id: I827d913c14334b493b46977a827d44e72143fa4e
QUICHE (QUIC, Http/2, Etc) is Google‘s implementation of QUIC and related protocols. It powers Chromium as well as Google’s QUIC servers and some other projects.