Remove usage of ScopedAsyncTaskScheduler from string_message_codec_unittest.cc.

ScopedAsyncTaskScheduler is deprecated.

Bug: 708584
Change-Id: I886855c04dc8945870f4ceea0f100ed9311088f0
Reviewed-on: https://chromium-review.googlesource.com/591697
Commit-Queue: Francois Doray <fdoray@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493720}
1 file changed