Revert "Make WatchedFramePop instrumentation event pure-virtual"

Builds on top of a change that breaks tests.

This reverts commit a0e0f103956fab23d1bfb08a69dadb0bc81d1a35.

Change-Id: I6a35fc2f4a099e807b5ed81b93a3f9a8d8beeea2
4 files changed