Verify display ID instead for WindowContext#getDisplay

... because we make WindowContext#getDisplay associate with
WindowContext's resources to prevent the mismatch between
window metrics and display metrics of window context.

Bug: 190019118
Test: atest ContextGetDisplayTest
Change-Id: Ie51ddc3893c1b8734fcfdd7036a7ac80e05f6d30
1 file changed