Can you please test this on a non-Mac?  Mac has a different implementation of this infobar that all other platforms.  Until I hear back, I'm tentatively marking this as a Mac-only bug.

Removing omnibox label.  I know this feature is triggered by the omnibox, but this UI is not within the omnibox or omnibox code at all.

Also removing navigation label.

explicitly to shrike@ to triage, as I don't know who owns this code

tapted@ - can you take a look?

Can you give more detailed repro instructions? I can't get that infobar to pop up on demand, and ChromeOmniboxNavigationObserver has no tests that I can find.

This might be an autolayout thing. Is this a regression?

I suspect this - https://cs.chromium.org/chromium/src/chrome/browser/ui/cocoa/infobars/alternate_nav_infobar_controller.mm

[AlternateNavInfoBarDelegate addAdditionalControls] calls [self removeButtons] which does

- (void)removeButtons {
  // Extend the label all the way across.
  NSRect labelFrame = [label_.get() frame];
  labelFrame.size.width = NSMaxX([cancelButton_ frame]) - NSMinX(labelFrame);

this relies on 

a layout of cancelButton_, but addAdditionalControls is called from awakeFromNib before autoresizing masks are set up.

Auto Layout is still turned off. I can look at it eventually, but have a bunch of other things on my plate right now.

FYI, an update/correction to comment #4: ChromeOmniboxNavigationObserver now has tests.

*** UI Mass triage ***

adding labels for expert review.