GitLab

Use CronetURLRequestAdapter::PostTaskToNetworkThread instead of posting the task
directly to network thread to make sure the start/stop netlog task is executed
after request context is fully initialized.

Also changed the test cases to make sure that we don't regress.

BUG=470196

Review URL: https://codereview.chromium.org/996163005

Cr-Commit-Position: refs/heads/master@{#322577}