Able to reproduce this issue on Ubuntu 14.04 using chrome latest Dev #59.0.3030.0. Unable to repro on Mac OS 10.12.

Bisect Information:
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Using the per-revision bisect providing the bisect results,

You are probably looking for a change made after 447409 (known good), but no later than 447410 (first known bad).

CHANGE-LOG URL:
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https://chromium.googlesource.com/chromium/src/+log/5402cd7f4d105ca765798503fa0aecfe69035ca5..8e02f7a0f2fcf2ce37fc4cd26b98f35f86eb2a9e

From the CL above, assigning the issue to the concern owner
Review-Url: https://codereview.chromium.org/2663993002

thomasanderson@ Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Thanks!

This occurs on all desktop platforms (just tested on Mac, which gives a blue border).  The change in #1 exposed the problem on Linux.

The problem is the page is rendering a focus ring (the color you get around an element when you press tab to select it), so assigning to eae@ for further triage.

Focus outlines uses outline painting which is layout independent. Over to paint for further triage.

I can't reproduce this on Windows Version 59.0.3033.1 canary SyzyASan, Mac 59.0.3032.0 Canary, or Linux ToT. But that may be because I can't get YouTube to show video framed the way it is in the screen cast attached to this bug.

When I exit DevTools, the video is always shown full width across the screen with no gutter, hence no visible focus ring (I can't see a focus ring around the video either). It's worth noting that the page retains the mobile layout when DevTools is closed. This bug is not present on the desktop site.

And given it's only for users of DevTools, with YouTube, the priority is not high even if it can be reproduced.

This is a regression, so marking as stable blocking.

I can repro something similar on Mac. Don't think it is a regression, removing
that label.

Is this even a bug? Showing focus outlines is a feature. Is the focus outline
wrong?

I think it's an artifact of what happens when you leave DevTools on desktop when coming from device emulation. It's a bug in that you don't get back to where you started from if you go to DevTools, emulate mobile, and return. But in that sense it's minor compared to the fact that we don't re-layout the page with desktop style.

The repro steps also make me wonder if it's a DevTools transition bug whereby the video element gets focus because you had to click on it in the mobile emulation to make the video play. I don't think the video was even focusable using tab index on desktop.

There doesn't seem to be anything we should act on here.