I ran optimize-png-files.sh -o2 on chrome/android/java/res/.
This is result for (x)xxhdpi subfolders.

The small (~10 bytes) optimizations were ignored.

Overall: 11345 bytes saved, originally 103007 bytes -> 11%.

Results log:

drawable-xxhdpi/add_circle_blue.png: 3067 => 902 (2165 bytes: 70%)
drawable-xxhdpi/btn_tab_close.png: 333 => 162 (171 bytes: 51%)
drawable-xxhdpi/google_icon_sprite.png: 7087 => 7026 (61 bytes: 0%)
drawable-xxhdpi/google_logo.png: 13386 => 12911 (475 bytes: 3%)
drawable-xxhdpi/ic_email_googblue_36dp.png: 759 => 710 (49 bytes: 6%)
drawable-xxhdpi/ic_get_app_white_24dp.png: 369 => 174 (195 bytes: 52%)
drawable-xxhdpi/infobar_subresource_filtering.png: 1061 => 498 (563 bytes: 53%)
drawable-xxhdpi/ntp_signin_promo_card_single.9.png: 872 => 445 (427 bytes: 48%)
drawable-xxhdpi/physical_web_logo_anim1.png: 12720 => 12653 (67 bytes: 0%)
drawable-xxhdpi/physical_web_logo_anim2.png: 13871 => 13836 (35 bytes: 0%)
drawable-xxhdpi/search_sogou.png: 35117 => 35013 (104 bytes: 0%)
drawable-xxhdpi/settings_usb.png: 1167 => 472 (695 bytes: 59%)
drawable-xxxhdpi/add_circle_blue.png: 4351 => 1246 (3105 bytes: 71%)
drawable-xxxhdpi/btn_tab_close.png: 414 => 196 (218 bytes: 52%)
drawable-xxxhdpi/ic_email_googblue_36dp.png: 958 => 934 (24 bytes: 2%)
drawable-xxxhdpi/ic_fast_forward_white_36dp.png: 652 => 625 (27 bytes: 4%)
drawable-xxxhdpi/ic_get_app_white_24dp.png: 575 => 209 (366 bytes: 63%)
drawable-xxxhdpi/ic_skip_next_white_36dp.png: 506 => 434 (72 bytes: 14%)
drawable-xxxhdpi/ic_skip_previous_white_36dp.png: 525 => 442 (83 bytes: 15%)
drawable-xxxhdpi/infobar_subresource_filtering.png: 1608 => 716 (892 bytes: 55%)
drawable-xxxhdpi/ntp_signin_promo_card_single.9.png: 1233 => 600 (633 bytes: 51%)
drawable-xxxhdpi/omnibox_info.png: 842 => 822 (20 bytes: 2%)
drawable-xxxhdpi/settings_usb.png: 1534 => 636 (898 bytes: 58%)

BUG=702553

Review-Url: https://codereview.chromium.org/2754143004
Cr-Commit-Position: refs/heads/master@{#458769}