Merge "Only create DesktopModeController when flag is on" into tm-qpr-dev am: 64e177c0

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20600222



Change-Id: Icfb29be95eab2a193d4cb187760b5db99d6cdbc6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>