The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9845d25e5ab228c1a4203817c419f3156bba90a4

commit 9845d25e5ab228c1a4203817c419f3156bba90a4
Author: shrike <shrike@chromium.org>
Date: Thu Mar 17 23:32:44 2016

kThemePackVersion comment should mention theme cache flushing.

The comment should mention that bumping the version also flushes the
theme cache. I had intended to add that with my recent change but it
slipped my mind. Having the mentioned explicitly would have helped me
when working on the theme regression that needed the version number bump.

BUG= 595510 

Review URL: https://codereview.chromium.org/1811803002

Cr-Commit-Position: refs/heads/master@{#381835}

[modify] https://crrev.com/9845d25e5ab228c1a4203817c419f3156bba90a4/chrome/browser/themes/browser_theme_pack.cc