adhd: Fix memory leaks in fmt_conv_unittest and dev_stream_unittest

BUG=chromium:857597
TEST=FEATURE=test USE=asan emerge-amd64-generic adhd

Change-Id: Ie762c787bd1226e2d7f19c99c3d7a6fc86f1d8b5
Reviewed-on: https://chromium-review.googlesource.com/1126882
Commit-Ready: Chih-Yang Hsia <paulhsia@chromium.org>
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
2 files changed