AutoScrollExtensionSettingsWebUITest.testAutoScroll browser test is flaky on Mac Trunk - Continuous Builder

Link to Builder
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https://uberchromegw.corp.google.com/i/official.desktop.continuous/builders/mac%20trunk/builds/47767

Link to Log File
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https://uberchromegw.corp.google.com/i/official.desktop.continuous/builders/mac%20trunk/builds/47766/steps/browser_tests/logs/stdio

Log File Contents
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=================
AutoScrollExtensionSettingsWebUITest.testAutoScroll (run #1):
[ RUN      ] AutoScrollExtensionSettingsWebUITest.testAutoScroll
[79810:33795:0404/140153.099859:ERROR:service_manager.cc(480)] InterfaceProviderSpec prevented connection from: content_utility to: content_browser
[79810:771:0404/140153.442903:INFO:CONSOLE(5)] "line1", source: chrome-extension://pdlpifnclfacjobnmbpngemkalkjamnf/script.js (5)
[79810:771:0404/140153.443226:INFO:CONSOLE(6)] "line2", source: chrome-extension://pdlpifnclfacjobnmbpngemkalkjamnf/script.js (6)
[79810:771:0404/140154.409171:INFO:CONSOLE(1221)] "Running TestCase AutoScrollExtensionSettingsWebUITest.testAutoScroll", source: test_api.js (1221)
[79810:771:0404/140154.409372:WARNING:CONSOLE(0)] "/deep/ combinator is deprecated and will be a no-op in M60, around August 2017. See https://www.chromestatus.com/features/4964279606312960 for more details.", source:  (0)
[79810:771:0404/140154.490406:ERROR:CONSOLE(0)] "Uncaught (in promise) AssertionError: expected 0 to be above 0", source: chrome://extensions-frame/?id=ldnnhddmnhbkjipkidpdiheffobcpfmf (0)
BrowserTestBase received signal: Terminated: 15.

Possible suspect
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https://chromium.googlesource.com/chromium/src/+/5079d8944bb80c049f8ecab6128cb71b04c245a7

Assigning to the CL owner for further updates.