I ran tools/resources/optmize-png-files.sh on:
  ui/file_manager/audio/assets/
  ui/file_manager/file_manager/foreground/images
  ui/file_manager/gallery/images
  ui/file_manager/video_player/images

The resource size (/opt/google/chrome/resources.pak) changes
from 42641939 bytes to 42417396 bytes (219KB saved)

The image quality should stay the same as the optimization
process doesn't lose any information.

Bug: 1017111
Test: Manually confirmed images look same on the device (not all the images, though)
Change-Id: Id37286924fcd94440791e2dd31a883437eb7f49a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1875861Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708898}