Windows may return a DesktopCoordinate out of the first quadrant
(x >= 0 && y >= 0), this typically happens when the primary and secondary
monitors are swapped. i.e. The secondary monitor is on the left but the primary
one is on the right.
This change "moves" the entire screen from any quadrant to the (0, 0), so we can
capture the monitors in other quadrants.
BUG=chromium:715689
Review-Url: https://codereview.webrtc.org/2848443004
Cr-Commit-Position: refs/heads/master@{#17935}
049ec71e65