Stop WebSocket SubProtocolIsUsed test crashing

WebSocketMultiProtocolStreamCreateTest.SubProtocolIsUsed would crash if
a stream failed to be created. Make it assert instead, so other tests
can still run.

Verified that other tests in websocket_stream_test.cc do not have the
same issue.

Change-Id: If50129d3ad2339398e23eb67fe1c5e05fca3615a
Reviewed-on: https://chromium-review.googlesource.com/1076569
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562720}
1 file changed