Interestingly enough, the RTL layout correctness for the rest of the bubble isn't guarded by the "experimental RTL" flag, but straight up "is this an RTL language" flag.

I think that flag was introduced in August/September-ish (some time shortly before I joined the team), so basically anything that made an effort at RTL before the current push wouldn't take it into account.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ae182230f56e92bc952ba62c8d6800e56f206008

commit ae182230f56e92bc952ba62c8d6800e56f206008
Author: avi <avi@chromium.org>
Date: Fri Apr 28 22:34:37 2017

[Mac RTL] Fix the RTLness of the website settings bubble header.

BUG= 696009 

Review-Url: https://codereview.chromium.org/2714193004
Cr-Commit-Position: refs/heads/master@{#468159}

[modify] https://crrev.com/ae182230f56e92bc952ba62c8d6800e56f206008/chrome/browser/ui/cocoa/page_info/page_info_bubble_controller.mm