The two suspects are:
https://codereview.chromium.org/2850333002
https://codereview.chromium.org/2857773002

My guess is the latter? Disabling tests in the meantime.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2e1c1951bdfd584c7b076020071ff2596d89d909

commit 2e1c1951bdfd584c7b076020071ff2596d89d909
Author: msramek <msramek@chromium.org>
Date: Wed May 03 09:31:59 2017

Disable element-instance-property-listing, global-interface-listing

The tests:
virtual/stable/webexposed/element-instance-property-listing.html
virtual/stable/webexposed/global-interface-listing.html

are failing on all Blink bots.

NOTRY=True
TBR=alph@chromium.org,pfeldman@chromium.org
BUG= 717914 

Review-Url: https://codereview.chromium.org/2854213003
Cr-Commit-Position: refs/heads/master@{#468926}

[modify] https://crrev.com/2e1c1951bdfd584c7b076020071ff2596d89d909/third_party/WebKit/LayoutTests/TestExpectations

Two things come to mind here
1) The failing test is payment request. It was only enabled here:
https://codereview.chromium.org/2855923002   I believe this should be assigned to mathp@ it is likely that change.

2) These tests should *never* be disabled. They are a safeguard in that we aren't exposing things to the outside world that we shouldn't. Copying rbyers@ so he is aware from a predictability point of view.

http://crrev.com/2856193002

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/259bce9e315438c00d7d660b446de65b6b03c360

commit 259bce9e315438c00d7d660b446de65b6b03c360
Author: rouslan <rouslan@chromium.org>
Date: Thu May 04 22:49:50 2017

Update global interface listing for web payments API on desktop.

This patch updates the global interface listing after PaymentRequest was
enabled on additional platforms: Windows, Mac, ChromeOS, Linux.

blink-dev@ announcement:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/p1DYoxHlkKg/g_ZW1YLDCgAJ

This patch also re-enables global interface listing tests, which should
never be disabled.

BUG= 717914 

Review-Url: https://codereview.chromium.org/2856193002
Cr-Commit-Position: refs/heads/master@{#469497}

[modify] https://crrev.com/259bce9e315438c00d7d660b446de65b6b03c360/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/259bce9e315438c00d7d660b446de65b6b03c360/third_party/WebKit/LayoutTests/platform/mac/virtual/stable/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/259bce9e315438c00d7d660b446de65b6b03c360/third_party/WebKit/LayoutTests/platform/win/virtual/stable/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/259bce9e315438c00d7d660b446de65b6b03c360/third_party/WebKit/LayoutTests/virtual/stable/webexposed/element-instance-property-listing-expected.txt

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/948317e5fe39e679b776bfd732dd50c4215bd191

commit 948317e5fe39e679b776bfd732dd50c4215bd191
Author: johnme <johnme@chromium.org>
Date: Fri May 05 15:59:04 2017

[WebView global interface listing] Mark Web Payments as not exposed

Fix WebViewLayoutTest#testWebViewIncludedStableInterfaces which is
currently failing because the Web Payments API is not currently
supported on WebView ( crbug.com/667069 ), but was missing from the list
of APIs expected to be missing.

BUG= 667069 , 717914 
TBR=rouslan@chromium.org,zkoch@chromium.org,timvolodine@chromium.org
NOTRY=true
SKIPTREECHECKS=true

Review-Url: https://codereview.chromium.org/2862583009
Cr-Commit-Position: refs/heads/master@{#469665}

[modify] https://crrev.com/948317e5fe39e679b776bfd732dd50c4215bd191/android_webview/tools/system_webview_shell/test/data/webexposed/not-webview-exposed.txt

Removing Sherrif-Chromium label, as this is being addressed.