Update refresh rate callback docs to include DisplayManager caveat.

Display#getRefreshRate is eventually consistent, so callbacks that call into DisplayManager may misbehave without polling, which is brittle. This will not be fixed until Android 12 at the earliest, so document this for Android 11.

Bug: 161725670
Change-Id: I0557c1e18747ee69eba5ea39c6e974873bdee5a0
1 file changed