Revert "Stop using NotificationService in ContentStabilityMetrics..."

This reverts commit 1d9db55e (crrev.com/963059), due to suspected
impact on Stability.Counts2.PageLoad.

On Android, the #if guard around LogRendererCrash from crrev.com/981826
is preserved.

Bug: 1330982e,357627,1174762,1174769
Change-Id: I5bb72c03055e03e6551cf418ee9f50704a013b9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3792464


Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Bo Liu <boliu@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1029930}