The step was constantly failing from 
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45055

The failing tests are:
__main__.InstallerTest.MigrateMultiStrandedBinariesOnInstall
__main__.InstallerTest.MigrateMultiStrandedBinariesOnUpdate
__main__.InstallerTest.ChromeSystemLevel
__main__.InstallerTest.MigrateMultiNoBinaries
__main__.InstallerTest.ChromeUserLevel
__main__.InstallerTest.ChromeSystemLevelUpdate
__main__.InstallerTest.MigrateMultiSimple
__main__.InstallerTest.ChromeUserLevelUpdate

logs from https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45055

==============
ChromeUserLevelUpdate: no_pv -> install_chrome_user -> chrome_user_installed_not_inuse -> update_chrome_user -> chrome_user_updated_not_inuse -> test_chrome_with_chromedriver_user -> chrome_user_installed_not_inuse -> uninstall_chrome_user -> clean
 ... [1101/210414:test_installer.py(187)] Verifying state no_pv
[1101/210414:test_installer.py(154)] Beginning action install_chrome_user
[1101/210418:test_installer.py(157)] Finished action install_chrome_user
[1101/210418:test_installer.py(187)] Verifying state chrome_user_installed_not_inuse
[1101/210418:test_installer.py(154)] Beginning action update_chrome_user
[1101/210421:test_installer.py(157)] Finished action update_chrome_user
[1101/210421:test_installer.py(187)] Verifying state chrome_user_updated_not_inuse
[1101/210421:test_installer.py(154)] Beginning action test_chrome_with_chromedriver_user
[1101/210423:test_installer.py(228)] stdout:
[1101/210423:test_chrome_with_chromedriver.py(76)] 
Traceback (most recent call last):
  File "test_chrome_with_chromedriver.py", line 132, in <module>
    sys.exit(main())
  File "test_chrome_with_chromedriver.py", line 121, in main
    with CreateChromedriver(args) as driver:
  File "e:\b\s\w\ir\cipd_bin_packages\bin\Lib\contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "test_chrome_with_chromedriver.py", line 72, in CreateChromedriver
    chrome_options=chrome_options)
  File "e:\b\s\w\ir\cache\builder\src\chrome\test\mini_installer\..\..\..\third_party\webdriver\pylib\selenium\webdriver\chrome\webdriver.py", line 66, in __init__
    desired_capabilities=desired_capabilities)
  File "e:\b\s\w\ir\cache\builder\src\chrome\test\mini_installer\..\..\..\third_party\webdriver\pylib\selenium\webdriver\remote\webdriver.py", line 64, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "e:\b\s\w\ir\cache\builder\src\chrome\test\mini_installer\..\..\..\third_party\webdriver\pylib\selenium\webdriver\remote\webdriver.py", line 106, in start_session
    'desiredCapabilities': desired_capabilities,
  File "e:\b\s\w\ir\cache\builder\src\chrome\test\mini_installer\..\..\..\third_party\webdriver\pylib\selenium\webdriver\remote\webdriver.py", line 157, in execute
    self.error_handler.check_response(response)
  File "e:\b\s\w\ir\cache\builder\src\chrome\test\mini_installer\..\..\..\third_party\webdriver\pylib\selenium\webdriver\remote\errorhandler.py", line 149, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: u"unknown error: Chrome failed to start: crashed\n  (unknown error: DevToolsActivePort file doesn't exist)\n  (The process started from chrome location C:\\Users\\chrome-bot\\AppData\\Local\\Chromium\\Application\\chrome.exe is no longer running, so ChromeDriver is assuming that Chrome has crashed.)\n  (Driver info: chromedriver=2.43.604830 (d4727fc8a6b1360e39869aa3e657e025de86dc7d),platform=Windows NT 6.1.7601 SP1 x86_64)" 
ERROR
==============


Logs from the latest run are the same
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45065

As for the CLs, there is nothing immediately suspicious in https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45055

Possible candidates:
Roll catapult https://chromium-review.googlesource.com/c/1313689
Roll src-internal https://chromium-review.googlesource.com/c/1313293
Roll pdfium https://chromium-review.googlesource.com/c/1313296

cc'ing mini_installer OWNERS, since I am not sure how to fix this.

Oh, looks like this has already happened before.

From https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45010 to https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45029

and from https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45000
to 
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45007

and from https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/44928
to https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/44940

and from https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/44883 to https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/44884

The failing tests and logs are the same (I've selectively checked a couple).

The passing test log is (from https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/45054)
==============
ChromeUserLevelUpdate: no_pv -> install_chrome_user -> chrome_user_installed_not_inuse -> update_chrome_user -> chrome_user_updated_not_inuse -> test_chrome_with_chromedriver_user -> chrome_user_installed_not_inuse -> uninstall_chrome_user -> clean
 ... [1101/203839:test_installer.py(187)] Verifying state no_pv
[1101/203839:test_installer.py(154)] Beginning action install_chrome_user
[1101/203842:test_installer.py(157)] Finished action install_chrome_user
[1101/203842:test_installer.py(187)] Verifying state chrome_user_installed_not_inuse
[1101/203842:test_installer.py(154)] Beginning action update_chrome_user
[1101/203844:test_installer.py(157)] Finished action update_chrome_user
[1101/203844:test_installer.py(187)] Verifying state chrome_user_updated_not_inuse
[1101/203844:test_installer.py(154)] Beginning action test_chrome_with_chromedriver_user
[1101/203848:test_installer.py(157)] Finished action test_chrome_with_chromedriver_user
[1101/203848:test_installer.py(187)] Verifying state chrome_user_installed_not_inuse
[1101/203848:test_installer.py(154)] Beginning action uninstall_chrome_user
[1101/203849:test_installer.py(157)] Finished action uninstall_chrome_user
[1101/203849:test_installer.py(187)] Verifying state clean
ok
============

The earliest such failure is
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%207%20Tests%20x64%20%281%29/44806

 Issue 887623  is about the flakiness of MigrateMultiStrandedBinariesOnInstall.

Feel free to mark as a duplicate of 887623, if you like so.

I think that some/most of these flakes will be resolved by the revert at https://chromium-review.googlesource.com/c/chromium/src/+/1317569.