GitLab

Added tests similar to TestLauncher unittests to run
3 simple content tests and validate the TestLauncher json result file.

Common methods for validating resulting json file were
moved to test_launcher_test_utils.h/cc.

Bug: 936244
Change-Id: I8dee29f80f82ca5981f7343e9ffec4cacc95eeaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1743099Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Ilia Samsonov <isamsonov@google.com>
Cr-Commit-Position: refs/heads/master@{#688321}