This issue might relate to crbug.com/716174, where the boundary alignment seems different for video layer and the interstitial element (in media shadow dom) for some device scale factor.

karlo@: Feel free to assign it back if you think this is different. Thanks!

This might also be due to sub-pixel layer positioning which IIRC was recently landed.

It would only be related to crbug.com/716174 if there is a border around the video element, which doesn't seem to be the case. And that would happen in M-58 also. Could you verify those conditions and update the bug?

Note the link in the test case https://vimeo.com/193358188

I can't repro on Mac.

The media remoting interstitial was introduced from M59.
So far this issue was only reported on display with 1.5X device scale factor.

Repro steps:
1. Enable #media-remoting flag in chrome://flags.
2. Mirroring a tab to a ChromeCast receiver (build 1.23).
3. Start playing any video (e.g. a local video, or any vimeo video) in tab.
4. Fullscreen the video, and wait for media remoting starts with the interstitial shown locally.

Please note the issue doesn't happens for all sizes. So the browser window might need to be resized to repro.

re #3: That won't work in a Chromium build (need a Chrome-branded build).

We should wait for the other bug to be fixed, and then just re-check (on our end) whether this bug has been fixed.

This may have been fixed. Next time I have a local build going (since this repro'ed on my Linux Desktop very easily), I'll double-check.

dbbrooks@ can you please see whether you can repro in latest build?

Note that this only repro'ed on a desktop using a 1.5X device scaling factor. So, this will not repro on a Mac Retina (2X), or a traditional screen. (See original bug description for more details.)

dbbrooks: Ping.

BTW--You should be able to set up the repro conditions by launching chrome with the --force-device-scale-factor=1.5 flag. And, be sure to try a few different window sizes to make sure the width of the window is an odd number of pixels. :)

On Chrome 65.0.3325.31, I just:

1. launched Chrome with the --force-device-scale-factor=1.5 flag 
2. Triggered Media Remoting
3. Verified that I didn't see the bug.
4. Stopped Media Remoting, resized the browser window, re-triggered Media Remoting and did not see the bug.
5. Repeated step 4 a few times with different window sizes.

So as long as these steps are sufficient, I'll close this bug as Won't Fix, no repro.