Change const variables to constexpr in printer_description.cc

constexpr variables must be initialized and computed at compile-time,
unlike their const counterparts that can defer their initializations
to run-time. This change allows for a slight run-time performance
boost.

Correct a typo by changing the static variable kSizeTrasholdUm to
kSizeThresholdUm. The use of the variable is limited to
printer_description.cc.

Change-Id: I4e43df7666570fa37a15e8860a635badbac306e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937253
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721172}
1 file changed