GitLab

This method should be a const method to be consistent to NowTicks() in
base::TickClock, which is also converted to a const method at
http://crrev.com/821f0e338ebbe420

Bug: 789079
Change-Id: I6b5c9bcee2d730214298ae7a7136ea6b312ad079
Reviewed-on: https://chromium-review.googlesource.com/1001213
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550598}