GitLab

This used to store the original size prior to calibration but that
changed in r304472 ("Keep track of window -> displays mapping"). It no
longer behaves as documented & isn't necessary, so remove it.

TEST=compile
BUG=none

Review URL: https://codereview.chromium.org/1035513002

Cr-Commit-Position: refs/heads/master@{#322046}