Revert "Add IProcessObserver.OnProcessStarted API."

Revert submission 25758093-on-process-started

Reason for revert: Build breakage b/322242947

Reverted changes: /q/submissionid:25758093-on-process-started

Change-Id: I8bd883ecad0503bdbfceaef84319a311dbee10a8
10 files changed