Incognito icons on shortcut menu are out of date. All new pngs have
been optimized by tools/resources/optimize-png-files.sh.

Bug: 1067127
Change-Id: I9658692507363cb569dab99b4743f4c5a0ae0c08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2145969Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Lijin Shen <lazzzis@google.com>
Cr-Commit-Position: refs/heads/master@{#758558}