Fix freeze rate calculations am: 2a3af65a am: 6a1f5f28 am: d6b9981f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/23352136



Change-Id: I792f44e67c1b356e7682922353434502550b888a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>