Revert of [test] Refactoring - Use subject/observer pattern for progress indicators. (patchset #3 id:40001 of https://codereview.chromium.org/1171943002/)

Reason for revert:
might break stuff

Original issue's description:
> [test] Refactoring - Use subject/observer pattern for progress indicators.
>
> This should prevent bugs caused by missing super calls in
> overridden methods. The assumption is that methods of
> different indicators are independent.
>
> Committed: https://crrev.com/fbe973ff1722a6158a5b2babce9c1a32d26a1d3b
> Cr-Commit-Position: refs/heads/master@{#28866}

TBR=jkummerow@chromium.org,tandrii@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1163373005

Cr-Commit-Position: refs/heads/master@{#28869}