GitLab

If enable_video_with_mixed_audio is defined, unittests should not
include null_video source_set.

Bug: 80443515
Test: manual / CQ
Change-Id: I905edbdc019841f1d2dfe18169ef3ba0af92b270
Reviewed-on: https://chromium-review.googlesource.com/1220697Reviewed-by: Sergey Volk <servolk@chromium.org>
Commit-Queue: Sunil Kumar <skx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590538}