Revert of Revert of [test] Refactoring - Use subject/observer pattern for progress indicators. (patchset #1 id:1 of https://codereview.chromium.org/1163373005/)

Reason for revert:
All build problems had other causes.

Original issue's description:
> 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
>
> Committed: https://crrev.com/2a3962d9d2a7415378811f4d56522531332d5a3e
> Cr-Commit-Position: refs/heads/master@{#28869}

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

Review URL: https://codereview.chromium.org/1176863002

Cr-Commit-Position: refs/heads/master@{#28901}