Chrome Version: 63.0.3220.0
OS: macOS 10.12

What steps will reproduce the problem?
(1) Launch Chrome in RTL (command line flags  -NSForceRightToLeftWritingDirection YES -AppleTextDirection YES --force-ui-direction=rtl --enable-features=MacRTL )
(2) Go to Content Settings
(3) Click Handlers

What is the expected result?
The Content Settings items should scroll off the page from left to right

What happens instead?
The items scroll from right to left, as they do in LTR mode. The horizontal scroll direction should be reversed for RTL. The UI gets other things right, like the left-pointing arrows at the left edge of the Handlers item, so Settings does know that it's in RTL mode.