Merge "Stop active MediaProjection callbacks before registering new callbacks"...

Merge "Stop active MediaProjection callbacks before registering new callbacks" into udc-qpr-dev am: 4beb9295 am: 079e769d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24678379



Change-Id: Ic994c8a4245752f55ddf561021dc2c57a4853212
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>