Clarified that some autofill interfaces can only be implemented by the system.

Test:  mmm -j frameworks/base/:doc-comment-check-docs

Fixes: 113323194

Change-Id: Ic0bea0e16fca0ce4c67d36f5611587843d7aad9f
(cherry picked from commit d5225e13d043a2d9e0cd0cfe8b584f18a4a2ae17)
2 files changed