The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/194ae154045ac6e880fae4ad14b3b4ca9f82e395

commit 194ae154045ac6e880fae4ad14b3b4ca9f82e395
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Thu Nov 15 13:48:13 2018

blink: use php7 for web tests on 10.14

php5 is unsupported, same as 10.13.

Bug: 892187
Change-Id: I52bc19b4f6ea8408093b7fcc61f6fe5153c984fd
Reviewed-on: https://chromium-review.googlesource.com/c/1335947
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608349}
[modify] https://crrev.com/194ae154045ac6e880fae4ad14b3b4ca9f82e395/third_party/blink/tools/blinkpy/web_tests/port/mac.py

There are now a lot of tests (~8000) that are failing, mostly with "image diff". I think that perhaps we need to create a mac-mac10.14 directory in third_party/blink/web_tests/platform/ and put the expectations for these tests in there. How do we do that?

Over to tkent@: I'm a bit out of my depth here, I could use either a lot of advice or some extra hands :)

You'd actually create a mac-mac10.13 directory, and move the 10.13-specific baselines there and put the baselines for 10.14 into mac/. 

robertma@ and/or foolip@ can probably help here.

So I've done this for 10.13. Essentially as Dirk said, we need to create new baselines for Mac 10.14.

I was hoping there would be fewer breakages this time than 10.12 -> 10.13, but looks like the number is on the same scale. The work itself isn't technical at all, but it's a lot of babysitting as we are talking about landing a CL with thousands of files (or multiple, split CLs if you want to minimize merge conflicts) and maintaining a suite to be green on a bot that is not on CQ.

You'd need to modify the following stuff:
0. Set up a Blink try bot for 10.14.

1. Port: https://cs.chromium.org/chromium/src/third_party/blink/tools/blinkpy/web_tests/port/mac.py?l=53&rcl=9b69b0c6203dc822162d903db77a63225aff4125
FALLBACK_PATHS['mac10.13'] = ['mac-mac10.13'] + FALLBACK_PATHS['mac10.14']

2. rebaseline config: https://cs.chromium.org/chromium/src/third_party/blink/tools/blinkpy/common/config/builders.json?l=74&rcl=4f51d5d775713e1b428ad8fa5ee131c411753f3c
Add a new entry for the 10.14 bot (remember to set is_try_builder to true).

3. Run `blink_tools.py rebaseline-cl` and sit back.

(You don't need to rename any baselines yourself. rebaseline-cl should take care of it.)

It is par for the course for Apple to make enough changes to their text rendering and form controls to break every pixel test in a major OS release. I think that's only *not* happened once or twice.

What is a blink try bot & is it different from a regular try bot?

+cc jbudorick@ for #5 - I think I need a bot to do this.

These are the blink trybots:

https://ci.chromium.org/search?q=blink-rel

They are different from the regular trybots in that (a) they are regular release builds, not DCHECK builds, and (b) they only run the layout_tests and not all of the test suites.

They are used by the blink tooling (like rebaseline-cl) to generate all of the new baselines for a change.

Yes, we should set up a 10.14 trybot.

I haven't done this kind of task, and have no time for it.

Okay - I will try to work through this. jbudorick@, I'm going to need a bot per #5 and #8.