In the past, implementations of copy to clipboard for each tab are different. "players" and "audio" tab use <textarea> hidden with display: none (and the popup has no title), "video capture" tab uses window.prompt() (and the popup has a title like expected.png).

In my CL at https://chromium-review.googlesource.com/c/520742/ , I unified them to all use <textarea> wrapped in <dialog> as it is more accessible.

Maybe you want to add a title for the <dialog>?

With respect to comment #1:
Yes,Adding title for the <dialog> for the respective Tabs.

Working on a patch.

Able to reproduce the issue on Windows 7,Mac 10.12.5 & ubuntu 14.04 using chrome latest Canary-61.0.3135.0.
Manual Bisect:
------------
Good build:61.0.3129.0-Revision-478840
Bad build:61.0.3131.0-Revision-479564

Per revision-bisect info:
-------------------------
You are probably looking for a change made after 478952 (known good), but no later than 478953 (first known bad).
CHANGELOG URL:
The script might not always return single CL as suspect as some perf builds might get missing due to failure.
  https://chromium.googlesource.com/chromium/src/+log/08012dc3513eaf24a8d44e5cd63add938ddd41e6..cc34cc148b5256fc5eb0ab46a14726be2557664d

Possible suspect:
----------------
https://chromium.googlesource.com/chromium/src/+/cc34cc148b5256fc5eb0ab46a14726be2557664d

Unable to assign to the suspect as it is having gmail account,tommi@assigning to you as you were listed as one of the review ers for this CL.

Could you please take a look & reassign to the right owner if it is not related to your change.
Thanks.

Making different popup title for each tab seems superfluous, I thinking to just put "Ctrl+C to copy to clipboard, unfocus to exit." (see attached). Does that work for you?

Deleted: Capture.PNG 21.7 KB

	Capture.PNG 21.7 KB View Download

CL at https://codereview.chromium.org/2950503002/, can't add you as reviewer since I can't see your email address.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a6fb6c2e7e8b6aa98ad097d44e0aed5eeb9ca220

commit a6fb6c2e7e8b6aa98ad097d44e0aed5eeb9ca220
Author: loorongjie <loorongjie@gmail.com>
Date: Sat Jul 22 19:11:07 2017

[media-internals] Add note to clipboard dialog

BUG= 734524 

Review-Url: https://codereview.chromium.org/2950503002
Cr-Commit-Position: refs/heads/master@{#488866}

[modify] https://crrev.com/a6fb6c2e7e8b6aa98ad097d44e0aed5eeb9ca220/content/browser/resources/media/media_internals.css
[modify] https://crrev.com/a6fb6c2e7e8b6aa98ad097d44e0aed5eeb9ca220/content/browser/resources/media/media_internals.html

I think this has been fixed now