Gosh. So.

 - These dialogs use StyledLabel for their Window Title
 - StyledLabel::GetPreferredSize() can't be trusted until the width is known (since it may word-wrap)
 - BubbleFrameView traditionally used title()->GetPreferredSize().height > 0 as an indicator whether room should be made for the title
 - That doesn't work for StyledLabel so r493962 took the stance that if a dialog was to set GetBubbleFrameView()->SetTitleView(..) then it means room should be made for the title
 - So this means the updated logic in BubbleFrameView::HasTitle() now thinks these dialogs want a title


That is, even though ManagePasswordsBubbleView calls SetTitleView() it doesn't actually want a title for this flavour of itself.

To fix, I think I need to change

bool BubbleFrameView::HasTitle() const {
  return custom_title_ != nullptr ||
         default_title_->GetPreferredSize().height() > 0 ||
         title_icon_->GetPreferredSize().height() > 0;
}

into something more complex, like

bool BubbleFrameView::HasTitle() const {
  return (custom_title_ != nullptr &&
          GetWidget()->widget_delegate()->ShouldShowWindowTitle()) ||
         (default_title_ != nullptr &&
          default_title_->GetPreferredSize().height() > 0) ||
         title_icon_->GetPreferredSize().height() > 0;
}


then also override WidgetDelegate::ShouldShowWindowTitle() in ManagePasswordsBubbleView so that BubbleFrameView doesn't have to rely on custom_view_->GetPreferredSize() to show/hide the title (since that is guaranteed to break if the StyledLabel title string ever changes).

-> https://chromium-review.googlesource.com/644389

That seems reasonable to me. Thanks for tackling this Trent!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c47591e9c88c52f8e6012a85a5c60000e22471c8

commit c47591e9c88c52f8e6012a85a5c60000e22471c8
Author: Trent Apted <tapted@chromium.org>
Date: Thu Aug 31 17:46:37 2017

When a dialog uses SetTitleView() also use ShouldShowWindowTitle().

For regular title views, BubbleFrameView decides whether to add
title margins based on the preferred height of the title view.

This doesn't work for StyledLabel titles. Generally, the preferred
height of label (styled or otherwise) is not meaningful until the
width is known (due to word wrapping). And knowing the width requires
knowing whether title margins are added. So for fancy titles,
BubbleFrameView would use whether a non-null fancy title was added
at all via SetTitleView(). But that doesn't cater to use-cases that
always set a title view, but sometimes don't want to show it.

To cater for this, use WidgetDelegate::ShouldShowWindowTitle() to
determine whether a title should be hidden, even if a dialog has
called SetTitleView().

Bug:  760663 
Change-Id: Ib0feaa6a7408dfdb3ca71f62e6f425abf64ed212
Reviewed-on: https://chromium-review.googlesource.com/644389
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#498915}
[modify] https://crrev.com/c47591e9c88c52f8e6012a85a5c60000e22471c8/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc
[modify] https://crrev.com/c47591e9c88c52f8e6012a85a5c60000e22471c8/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.h
[modify] https://crrev.com/c47591e9c88c52f8e6012a85a5c60000e22471c8/ui/views/bubble/bubble_dialog_delegate_unittest.cc
[modify] https://crrev.com/c47591e9c88c52f8e6012a85a5c60000e22471c8/ui/views/bubble/bubble_frame_view.cc

Should this be merged?

I don't think this meets the requirements of go/chrome-merges

(assuming you meant an m61 merge. I'm pretty sure this made the m62 cut)