Per the attachment on  bug 584342  comment 15, the icons should always be circular everywhere, and the glyph inside should only ever be an up arrow or an exclamation point.

And I'm going to go ahead and kick this over to you, Allen, since you already did the first part of the work here.

There is a third state dealing with plugin incompatibility. What icon should be shown in that state. Right now, the circle-with-line is shown for global errors and the circle-exclamation-point is showing for plugin-incompatibilities. I think they should be reversed.

Hmm. What's an example of a plugin incompatibility? Do you have a screenshot floating around? (In my head, we used page action-y UI and in-content-area placeholders for plugin stuff)

I'm not sure how to force such a state. I just know that there is code that handles this state. At one point I did add a command-line switch to force the state, similar to the --simulate-upgrade switch. It was removed at the behest of the reviewer(s). 

Since we basically only support Flash now in terms of plugins, maybe the plugin incompatibility code is unreachable?

You'd have to ask the authors/OWNERs of such code.

OK, I looked at the code more closely.  The incompatibility warning looks to be about incompatible DLLs rather than plugins.  The security folks probably have some of these sitting around to help you test.  See also the list in chrome/browser/win/enumerate_modules_model.cc .

I think we should probably just go ahead and use the ! icon for this state as well.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/891103c65108d1b54dce9786a72f64bab86a2bfc

commit 891103c65108d1b54dce9786a72f64bab86a2bfc
Author: kylixrd <kylixrd@chromium.org>
Date: Thu Jul 21 18:11:20 2016

Use app menu error icon for global error app menu items.

This makes sure the error icon is the circle with an exclamation point on both the app menu button and any error menu items within the menu itself.

BUG= 629204 

Review-Url: https://codereview.chromium.org/2166853002
Cr-Commit-Position: refs/heads/master@{#406906}

[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/chrome/browser/ui/cocoa/toolbar/app_toolbar_button.mm
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/chrome/browser/ui/global_error/global_error.cc
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/chrome/browser/ui/views/toolbar/app_menu_button.cc
[delete] https://crrev.com/ff574fee1d11575e1ffd55715accbbd97ebfbd96/ui/gfx/vector_icons/browser_tools.1x.icon
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/ui/gfx/vector_icons/browser_tools.icon
[delete] https://crrev.com/ff574fee1d11575e1ffd55715accbbd97ebfbd96/ui/gfx/vector_icons/browser_tools_error.1x.icon
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/ui/gfx/vector_icons/browser_tools_error.icon
[delete] https://crrev.com/ff574fee1d11575e1ffd55715accbbd97ebfbd96/ui/gfx/vector_icons/browser_tools_update.1x.icon
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/ui/gfx/vector_icons/browser_tools_update.icon
[delete] https://crrev.com/ff574fee1d11575e1ffd55715accbbd97ebfbd96/ui/gfx/vector_icons/browser_tools_warning.1x.icon
[delete] https://crrev.com/ff574fee1d11575e1ffd55715accbbd97ebfbd96/ui/gfx/vector_icons/browser_tools_warning.icon
[modify] https://crrev.com/891103c65108d1b54dce9786a72f64bab86a2bfc/ui/gfx/vector_icons_sources.gypi