GLSurfaceOzone: move the IsUDL() check after ScheduleOverlayPlanes()

The IsUDL() call always returns false if no overlay planes are queued.

BUG=569075
TEST=Verified that IsUniversalDisplayLinkDevice() returns true for UDL

Review URL: https://codereview.chromium.org/1564123002

Cr-Commit-Position: refs/heads/master@{#368155}
1 file changed