Merge "Clarify DelegateManagerCallback based on API review" am: 95fe9715bc am: 4678139c3b am: 8a42a47340

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1690269

Change-Id: Ia04a10a6843e56ca8617bd8fe696416e55a8a284