Issue chromedriver:2515  has been merged into this issue.

Headless is executing the wrong binary for child processes.

The CHILD_PATH_EXE is not being set in headless's ContentMainDelegate: https://cs.chromium.org/chromium/src/headless/lib/headless_content_main_delegate.cc?l=246&rcl=3df5254f608bfec7ee6407faed8c7232b935f318.

These lines are missing from Chrome's version: https://cs.chromium.org/chromium/src/chrome/app/chrome_main_delegate.cc?l=763&rcl=3df5254f608bfec7ee6407faed8c7232b935f318.

I'm not really sure how to fix this. Headless seems to implicitly depend on Chrome's binaries but doesn't seem to be allowed to actually reference Chrome's code, where things like kHelperProcessExecutablePath and chrome::GetVersionedDirectory() are defined.

Looks like I can move the chrome lines in #7 to SetUpBundleOverrides(), which is called here: https://cs.chromium.org/chromium/src/chrome/app/chrome_main.cc?l=95&rcl=c04a9a27665700d3697b59d74964bfae1aafe7f3

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229

commit 6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229
Author: Robert Sesek <rsesek@chromium.org>
Date: Wed Jul 25 17:09:54 2018

Fix headless mode under the MacV2Sandbox.

- The standalone headless_shell needs to invoke the Seatbelt server
  in its child processes.
- The --headless flag in Chrome needs to set up the CHILD_PROCESS_EXE
  override for finding the Helper.app. The --headless flag was incorrectly
  spawning the main app executable rather than the helper.

Bug:  866606 ,  689306 
Change-Id: I0e4fec109fad5577263059fd0b62dea3bb966860
Reviewed-on: https://chromium-review.googlesource.com/1148478
Reviewed-by: David Vallet <dvallet@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577949}
[modify] https://crrev.com/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229/chrome/app/chrome_main_delegate.cc
[modify] https://crrev.com/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229/chrome/app/chrome_main_mac.mm
[modify] https://crrev.com/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229/headless/BUILD.gn
[modify] https://crrev.com/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229/headless/app/DEPS
[modify] https://crrev.com/6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229/headless/app/headless_shell_main.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0af51910bbfe080bb9f669b77c250549dd393725

commit 0af51910bbfe080bb9f669b77c250549dd393725
Author: Artur Khachatryan <khachatryan@chromium.org>
Date: Thu Jul 26 04:13:39 2018

[ChromeDriver] Re-enable headless tests on Mac except for Chrome m69

Bug: chromedriver:2515  was blocked by chromium:866606, which is now fixed.
Re-enabling affected tests on Mac, but disabling them for Chrome m69
because the fix for chromium:866606 is not included in the Chrome m69
build used on the waterfall.

Bug:  chromedriver:2515 
Change-Id: I62025961187f184bdea6d0130c482cfb1a5ce411
Reviewed-on: https://chromium-review.googlesource.com/1150968
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578193}
[modify] https://crrev.com/0af51910bbfe080bb9f669b77c250549dd393725/chrome/test/chromedriver/test/run_py_tests.py

This bug is fixed and can be closed.

We should probably take this into M69, too.

This bug requires manual review: DEPS changes referenced in bugdroid comments.
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

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

Approving merge to M69 branch 3497 based on comment #14. Please merge ASAP. Thank you.

Please merge your change to M69 branch 3497 by 4:00 PM PT today, so we can pick it up for next week LAST M69 Dev release before Beta promotion. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0562c348616685f77f385776508013680f81601c

commit 0562c348616685f77f385776508013680f81601c
Author: Robert Sesek <rsesek@chromium.org>
Date: Fri Jul 27 16:31:13 2018

Fix headless mode under the MacV2Sandbox.

- The standalone headless_shell needs to invoke the Seatbelt server
  in its child processes.
- The --headless flag in Chrome needs to set up the CHILD_PROCESS_EXE
  override for finding the Helper.app. The --headless flag was incorrectly
  spawning the main app executable rather than the helper.

(cherry picked from commit 6a8df1b08fffbb4ca0ddb787b14ce362f0fc2229)

Bug:  866606 ,  689306 
Change-Id: I0e4fec109fad5577263059fd0b62dea3bb966860
Reviewed-on: https://chromium-review.googlesource.com/1148478
Reviewed-by: David Vallet <dvallet@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#577949}
Reviewed-on: https://chromium-review.googlesource.com/1153227
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/branch-heads/3497@{#155}
Cr-Branched-From: 271eaf50594eb818c9295dc78d364aea18c82ea8-refs/heads/master@{#576753}
[modify] https://crrev.com/0562c348616685f77f385776508013680f81601c/chrome/app/chrome_main_delegate.cc
[modify] https://crrev.com/0562c348616685f77f385776508013680f81601c/chrome/app/chrome_main_mac.mm
[modify] https://crrev.com/0562c348616685f77f385776508013680f81601c/headless/BUILD.gn
[modify] https://crrev.com/0562c348616685f77f385776508013680f81601c/headless/app/DEPS
[modify] https://crrev.com/0562c348616685f77f385776508013680f81601c/headless/app/headless_shell_main.cc