C2: add support for channel mask am: 65fab753 am: e0743832 am: 80c3091d am: f2b3443a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/17478658



Change-Id: I5c83b889e18d470d25a0acf1d25f61a773edf9eb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>