A CL failed CQ because of this flakiness:

CL: https://chromium-review.googlesource.com/c/554280
Link to failure:
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.win%2Fwin_chromium_x64_rel_ng%2F467527%2F%2B%2Frecipes%2Fsteps%2Fbrowser_tests__with_patch_%2F0%2Flogs%2FDiceBrowserTest.Signin%2F0

Very likely the culprit is https://chromium-review.googlesource.com/c/566817/
which changed that test 22 hours ago.

[1116:5672:0711/121040.637:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /favicon.ico
../../chrome/browser/signin/dice_browsertest.cc(300): error: Value of: token_requested_
  Actual: false
Expected: true
../../chrome/browser/signin/dice_browsertest.cc(301): error: Value of: refresh_token_available_
  Actual: false
Expected: true
../../chrome/browser/signin/dice_browsertest.cc(302): error: Value of: GetTokenService()->RefreshTokenIsAvailable(GetMainAccountID())
  Actual: false
Expected: true
[1116:5672:0711/121040.664:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /oauth2/v4/token
[1116:5672:0711/121040.664:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /oauth2/v4/token
[1116:4208:0711/121040.668:ERROR:event_page_request_manager.cc(147)] An error encountered while waking the event page.
[1116:4208:0711/121040.668:ERROR:event_page_request_manager.cc(89)] Draining request queue. (queue-length=3)
[1116:4208:0711/121040.668:ERROR:account_info_fetcher.cc(58)] OnGetTokenFailure: Request canceled.
[1116:4208:0711/121040.668:WARNING:account_fetcher_service.cc(305)] Failed to get UserInfo for main_gaia_id
[  FAILED  ] DiceBrowserTest.Signin, where TypeParam =  and GetParam() =  (1351 ms)
[ RUN      ] DiceBrowserTest.Signin
[3676:1152:0711/121041.830:ERROR:direct_composition_surface_win.cc(1007)] Failing to detect HDR, couldn't retrieve D3D11 device from ANGLE.
[3676:1152:0711/121041.833:INFO:media_foundation_video_encode_accelerator_win.cc(330)] Windows versions earlier than 8 are not supported.
[372:748:0711/121041.838:WARNING:chrome_browser_main_win.cc(475)] Command line too long for RegisterApplicationRestart:  --brave-new-test-launcher --cfi-diag=0 --gtest_also_run_disabled_tests --gtest_filter=DiceBrowserTest.Signin --single_process --test-launcher-bot-mode --test-launcher-summary-output="e:\b\swarm_slave\w\iogz9rem\output.json" --user-data-dir="C:\Users\CHROME~2\AppData\Local\Temp\scoped_dir5388_1666\d5388_29102" --disable-offline-auto-reload --gaia-url=https://127.0.0.1:60724/ --google-apis-url=https://127.0.0.1:60724/ --account-consistency=dice --no-first-run --no-default-browser-check --enable-logging=stderr --log-level=0 --safebrowsing-disable-auto-update --disable-default-apps --wm-window-animations-disabled --disable-component-update --test-type=browser --force-color-profile=srgb --disable-zero-browsers-open-for-tests --ipc-connection-timeout=30 --allow-file-access-from-files --dom-automation --log-gpu-control-list-decisions --disable-backgrounding-occluded-windows --disable-gl-drawing-for-tests --override-use-software-gl-for-tests --force-color-profile=srgb --disable-features=NetworkPrediction --flag-switches-begin --flag-switches-end --restore-last-session about:blank
[3676:1152:0711/121041.890:ERROR:gl_surface.cc(198)] NOT IMPLEMENTED
[3676:1152:0711/121041.895:ERROR:gl_surface.cc(198)] NOT IMPLEMENTED
[3676:1152:0711/121042.001:ERROR:gl_surface.cc(198)] NOT IMPLEMENTED
[3676:1152:0711/121042.005:ERROR:gl_surface.cc(198)] NOT IMPLEMENTED
[372:2120:0711/121042.137:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /favicon.ico
../../chrome/browser/signin/dice_browsertest.cc(300): error: Value of: token_requested_
  Actual: false
Expected: true
../../chrome/browser/signin/dice_browsertest.cc(301): error: Value of: refresh_token_available_
  Actual: false
Expected: true
../../chrome/browser/signin/dice_browsertest.cc(302): error: Value of: GetTokenService()->RefreshTokenIsAvailable(GetMainAccountID())
  Actual: false
Expected: true
[372:2120:0711/121042.156:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /oauth2/v4/token
[372:2120:0711/121042.156:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /oauth2/v4/token
[372:748:0711/121042.162:ERROR:oauth2_access_token_fetcher_impl.cc(250)] Unexpected persistent error: http_status=404
[372:748:0711/121042.162:ERROR:account_info_fetcher.cc(58)] OnGetTokenFailure: Invalid credentials.
[372:748:0711/121042.163:WARNING:account_fetcher_service.cc(305)] Failed to get UserInfo for main_gaia_id
[372:748:0711/121042.163:ERROR:oauth2_access_token_fetcher_impl.cc(250)] Unexpected persistent error: http_status=404
[372:748:0711/121042.168:ERROR:event_page_request_manager.cc(147)] An error encountered while waking the event page.
[372:748:0711/121042.168:ERROR:event_page_request_manager.cc(89)] Draining request queue. (queue-length=3)
[372:748:0711/121043.077:WARNING:url_request_context_getter.cc(43)] URLRequestContextGetter leaking due to no owning thread.
[  FAILED  ] DiceBrowserTest.Signin, where TypeParam =  and GetParam() =  (1356 ms)