fmalita@ originally suggested it could be related to https://chromium-review.googlesource.com/c/569007.

The current expected png looks a bit wrong (the arrows are too big...):

https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/forms/calendar-picker/calendar-picker-appearance-zoom125-expected.png

Does anyone know what determines the appearance of those arrows on input forms on Mac and why they might be different on different test runs?

Removing from Sheriff queue; the next step here after marking the tests as flaky is to find someone who might know about appearance of input widgets on Mac and what could cause flakiness.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b6c97cd8784b662059cb5b04de50544298dd5130

commit b6c97cd8784b662059cb5b04de50544298dd5130
Author: Quinten Yearsley <qyearsley@google.com>
Date: Fri Jul 14 18:18:07 2017

Add flaky expectations for calendar-picker tests on mac 10.9

TBR in order to green up the waterfall

TBR: fmalita
Bug:  743068 
Change-Id: Ic94118d288b7d1a4568e95df2538cef0542cb007
Reviewed-on: https://chromium-review.googlesource.com/572041
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486813}
[modify] https://crrev.com/b6c97cd8784b662059cb5b04de50544298dd5130/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/b6c97cd8784b662059cb5b04de50544298dd5130/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/forms/calendar-picker/calendar-picker-appearance-zoom125-expected.png

calendar-picker-appearance-zoom125.html and calendar-picker-appearance-zoom200.html are failing consistently.  I'll try rebaseline.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/94695916973a283066fcb263a4789843c6ca79e4

commit 94695916973a283066fcb263a4789843c6ca79e4
Author: Kent Tamura <tkent@chromium.org>
Date: Fri Jul 21 07:29:16 2017

Rebaseline calendar-picker-appearance-zoom125.html and calendar-picker-appearance-zoom200.html for Mac10.9.

TBR=qyearsley@chromium.org
NOTRY=true

Bug:  743068 
Change-Id: I6b7e9bae599f22c80bdb420d76d2f238408e37af
Reviewed-on: https://chromium-review.googlesource.com/579902
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488610}
[modify] https://crrev.com/94695916973a283066fcb263a4789843c6ca79e4/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/forms/calendar-picker/calendar-picker-appearance-zoom125-expected.png
[modify] https://crrev.com/94695916973a283066fcb263a4789843c6ca79e4/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/forms/calendar-picker/calendar-picker-appearance-zoom200-expected.png

Still flaky.

https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_tests&tests=fast%2Fforms%2Fcalendar-picker%2Fcalendar-picker-appearance-zoom

We've dropped support for the layout tests on 10.9, so we can close this.