Chrome Version: 68.0.3404.0 (Official Build)Revision b44ed3c60b2d1558f6149dfc962e73aff3ee0afc-refs/heads/master@{#552603} (64-bit)
OS: Mac OS X(10.12.6,10.13.1,10.13.5)

What steps will reproduce the problem?
(1)Launch chrome and navigate to http://foersom.com/net/HowTo/data/OoPdfFormExample.pdf
(2)Enter any text for e.g 'test' in name field or any field
(3)Now right click on text field > click 'select all' option from context menu, observe.

Actual: Alphabet 'A' appears in text field after clicking on 'select all' option from context menu.

Expected: Text entered should get selected after clicking on 'select all' option from context menu.

This is a regression issue broken in 'M68' and below is the manual bisect info
Good Build: 68.0.3399.0(Revision:551555)
Bad Build:  68.0.3400.0(Revision:551875)

(Unable to narrow down the range using per-revision bisect, hence providing the bisect using old script)
Narrow Bisect info:
You are probably looking for a change made after 539675 (known good), but no later than 539724 (first known bad).
CHANGELOG URL:

https://chromium.googlesource.com/chromium/src/+log/43cfb0c69fb23109a3ca3c5945e2470e098f1808..98ba09813ef6e8262f590117f6c684fdbeab05a3?pretty=fuller&n=30
Suspecting: r551652 ?

@thestig: 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.

Note: Issue not seen on Windows (7,8,8.1,10) & Linux (14.04 LTS) OS
 

Deleted: Actual_Result.mov 1.5 MB

	Actual_Result.mov 1.5 MB View Download