GitLab

The goal of this cl is to move all child process logic to TestLauncher.
This should simplify the gtest launcher structure and clarify
each class responsibilities.

TestRunner controls running test processes across sequence runners.

TestLauncherDelegate is now limited to provide test specific needs.
Command line for tests, timeout, result processing, etc.

This allows us to remove the ProcessLifetimeObserver and its extending
classes

The original change has been reverted since result processing
was not thread safe.

Bug: 936248,848465
Change-Id: I2468cf2e92901c7f2c4a6f42838be219397a7b0a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1721429
Commit-Queue: Ilia Samsonov <isamsonov@google.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682916}