Is this  bug 880122 ?

Unable to reproduce the issue on reported chrome version 69.0.3497.100 using Windows 10. Attaching screen-cast for reference.
Steps: 
---------
1. Launched reported chrome 
2. Downloaded the attached html file and dropped in to new tab 
As we are observed that " The text inside the element on top of the iframe was selected by clicking and dragging.

@Reporter: Could you please check the attached screen cast and please let us know if anything missed from our end and Request you to retry this issue with fresh profile without any extensions  & apps or reset all the flags and let us know if issue still persists.

Thanks.!

Deleted: 886906.mp4 3.6 MB

	886906.mp4 3.6 MB View Download

Saddly this is poor excuse saying "everything works on my machine". 
In our organization there are also divided PC's that either DO work or do NOT work, while testing this html. Same thing for our customers many of them report that it is not working so we had to switch back to using pdf.js which has it's own known bugs.

So clearly, there IS an issue with CHROME native pdf viewer.

I've tried using different chrome versions:
1. v68.0.3440.106 (Official Build) (64-bit) - test page worked.

2. Downloaded newer version and updated chrome to v69.0.3497.100 (Official Build) (64-bit) - relaunched chrome - test page stoped working.

@thestig Yes, it looks like it's a duplicate of the other issue. Seems like I missed it when I was searching for this exact bug. We could close this in favor of the other issue.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

I can also reproduce this error on any website that has an HTML element over an embedded PDF plugin.

I have an application where the user has to click a modal that's above a PDF and I can confirm this has been happening for a while, and more users are starting to report this issue to our support.

I am able to reproduce it easily by using Chrome Canary and newer versions of the Chrome Browser. I can also confirm this is happening on multiple platforms (I am certain of MacOS and Windows)

Embedding the PDF via <embed> <object> or <iframe> create the same effect. also by using "wmode=transparent" on those elements, which has been a workaround for similar  issues (embedded elements not respecting z-index).

Any CSS modifications also don't seem to have any effect on the behaviour. position, pointer-events, and z-index result in the same problem occurring.

Hello,

Investigation in our company we found out that it depends on chrome app settings.

In windows: %appdata%/local/google/chrome/user data/localstate file there is flag called: 'low_entropy_source2' with values of 930;5362;430 the problem is seen. With other values like 555 the problem is fixed.

%appdata%/local/google/chrome/user data/localstate does not seem to fix anything here

Starring this issue with the same reproduction as https://bugs.chromium.org/p/chromium/issues/detail?id=886906#c7

this does look like the other bug, so merging this bug to keep all the debug info in one place