[Media TTT] Use a listener pattern to notify about view removals. am: 5a7e9e6349

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21020063

Change-Id: Ib292e14c52e26fbf5eb676ecd9f6ac5300b65b26
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>