GitLab

Initialize the cached display device scale factor before usage.
Otherwise, the scale factor is 1 and the window is misplaced/sized.

I'll land a unit test separately, to make merging easier.

Bug: 899084, 665965
Test: KSV (Ctrl-Alt-/) search context menu supports display & UI scales.
Change-Id: Ie74cb70af33110aa09022d4dbb5c6d0069b6cc7c
Reviewed-on: https://chromium-review.googlesource.com/c/1311080
Commit-Queue: Michael Wasserman <msw@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605543}