Get display id from base view

When setting up dock, it is only guaranteed that the base view is
attached to the window so the display should be retrieved from that
view.

Bug: 369761469
Test: manual
Flag: NONE bugfix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:bd56d496a305a27a2861f59c9d44b75e94fa9bce)
Merged-In: I0c281ee63dd7748371920156ceb0311f4d34e6c5
Change-Id: I0c281ee63dd7748371920156ceb0311f4d34e6c5