Merge "WallpaperManager getDrawable & al clarifications" into udc-dev am: 5b1d2b53f5

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23027354

Change-Id: If4f18d872c661762db2dfea4121848b0a1b13280
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>