I'm seeing lots of failures of CursorsTest.SingleDocSelection in chromevox_tests on two ChromeOS bots in the CQ:
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_ozone_rel_ng

Some pass after retry, and some cause the try job to go red (potentially blocking the CQ), possibly because retries get disabled in some cases.  CC'ing sheriffs in case someone can take a look.

Examples:
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_ozone_rel_ng/builds/257960
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng/builds/300448

CursorsTest.SingleDocSelection (run #1):
[ RUN      ] CursorsTest.SingleDocSelection
[8621:8621:1021/073729:WARNING:chrome_browser_main_chromeos.cc(340)] Running as stub user with profile dir: test-user
[8621:8621:1021/073729:WARNING:audio_manager.cc(317)] Multiple instances of AudioManager detected
[8621:8621:1021/073729:WARNING:audio_manager.cc(278)] Multiple instances of AudioManager detected
[8621:8621:1021/073729:ERROR:logging_chrome.cc(173)] Unable to create symlink /tmp/.org.chromium.Chromium.kvLEzv/dUS6Eqh/test-user/chrome_debug.log pointing at /tmp/.org.chromium.Chromium.kvLEzv/dUS6Eqh/test-user/chrome_debug_20161021-073729.log: No such file or directory
[8621:8668:1021/073730:ERROR:drive_integration_service.cc(120)] /tmp should have been created as clear.
[8621:8671:1021/073730:WARNING:local_extension_cache.cc(259)] Extensions will not be installed from update URLs until /tmp/.org.chromium.Chromium.kvLEzv/dUS6Eqh/stub_device_local_extension_cache/.initialized exists.
[8621:8655:1021/073730:WARNING:freezer_cgroup_process_manager.cc(59)] Cgroup freezer does not exist or is not writable. Unable to freeze renderer processes.
ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default
[8621:8662:1021/073730:WARNING:alsa_util.cc(24)] PcmOpen: default,No such file or directory
ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default
[8621:8662:1021/073730:WARNING:alsa_util.cc(24)] PcmOpen: plug:default,No such file or directory
[8621:8662:1021/073730:ERROR:audio_output_resampler.cc(311)] Unable to open audio device in high latency mode.  Falling back to fake audio output.
[8621:8621:1021/073730:INFO:CONSOLE(813)] "Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (813)
[8621:8831:1021/073731:WARNING:simple_synchronous_entry.cc(1054)] Could not open platform files for entry.
[8621:8655:1021/073731:ERROR:component_loader.cc(90)] Can't load /usr/share/chromeos-assets/speech_synthesis/patts/manifest.json: Manifest file is missing or unreadable.
ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default
[8621:8662:1021/073731:WARNING:alsa_util.cc(24)] PcmOpen: default,No such file or directory
ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default
[8621:8662:1021/073731:WARNING:alsa_util.cc(24)] PcmOpen: plug:default,No such file or directory
[8621:8662:1021/073731:ERROR:audio_output_resampler.cc(311)] Unable to open audio device in high latency mode.  Falling back to fake audio output.
[1:1:1021/073731:INFO:render_accessibility_impl.cc(366)] Accessibility event: layoutComplete on node id 1
AXTreeUpdate tree data: doctype=html loaded=true loading_progress=1 mimetype=text/html url=about:blank focus_id=1 routing_id=2
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 664) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=about:blank html_tag=#document font_size=16

[8621:8621:1021/073731:INFO:CONSOLE(983)] "Speak (Q) category=nav "Alert"", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073731:INFO:CONSOLE(983)] "Speak (Q) category=nav "Connected to eth1"", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073731:INFO:CONSOLE(983)] "Speak (Q) category=nav """, source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073731:INFO:CONSOLE(983)] "Speak (Q) "ChromeVox spoken feedback is ready"", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073731:INFO:CONSOLE(7712)] "Running TestCase CursorsTest.SingleDocSelection", source: cursors_test.extjs (7712)
[8621:8659:1021/073732:ERROR:service_manager.cc(315)] Error: invalid Name: C17ED72B8D5EB1A658357B7B5A051F0C
[1,780756800:14:37:32.152514] Native Client module will be loaded at base address 0x0000716000000000
[8621:8621:1021/073732:INFO:CONSOLE(983)] "Speak (I) "tab created"", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073732:INFO:CONSOLE(867)] "Earcon object_open", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (867)
[8621:8621:1021/073732:INFO:CONSOLE(1705)] "Injecting into 2", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (1705)
[8621:8621:1021/073732:INFO:CONSOLE(2034)] "ChromeVox waiting for background page: data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p>. Will try again in 100ms", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVoxChromePageScript.js (2034)
[8621:8621:1021/073732:INFO:CONSOLE(983)] "Speak (I) "data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p>, tab"", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (983)
[8621:8621:1021/073732:INFO:CONSOLE(867)] "Earcon object_select", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (867)
[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: loadComplete on node id 1
AXTreeUpdate tree data: doctype=html loaded=true loading_progress=1 mimetype=text/html url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> focus_id=1 routing_id=2
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 664) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6
  id=4 group READONLY (8, 8)-(1084, 19) offset_container_id=1 background_color=&FFFFFFFF color=&FF000000 value= font_size=16 child_ids=8,11
    id=8 staticText READONLY (8, 8)-(37, 19) offset_container_id=1 name_from=contents background_color=&FFFFFFFF color=&FF000000 next_on_line_id=9 name=start value= display=inline font_size=16 child_ids=13
      id=13 inlineTextBox (0, 0)-(37, 19) offset_container_id=8 name_from=contents color=&FF000000 next_on_line_id=10 name=start value= character_offsets=8,15,24,31,37 word_starts=0 word_ends=5
    id=11 link FOCUSABLE READONLY (50, 8)-(149, 19) offset_container_id=1 name_from=contents background_color=&FFFFFFFF color=&FF0000EE text_style=underline name=google home page value= action=jump display=inline html_tag=a font_size=16 child_ids=14
      id=14 staticText READONLY (50, 8)-(149, 19) offset_container_id=1 name_from=contents background_color=&FFFFFFFF color=&FF0000EE text_style=underline previous_on_line_id=9 name=google home page value= action=click display=inline font_size=16 child_ids=15
        id=15 inlineTextBox (0, 0)-(149, 19) offset_container_id=14 name_from=contents color=&FF000000 previous_on_line_id=10 name=google home page value= character_offsets=10,20,30,40,44,54,59,69,79,95,105,110,120,130,140,150 word_starts=0,7,12 word_ends=6,11,16
  id=5 paragraph READONLY (8, 43)-(1084, 19) offset_container_id=1 background_color=&FFFFFFFF color=&FF000000 value= display=block html_tag=p font_size=16 child_ids=16
    id=16 staticText READONLY (8, 43)-(126, 19) offset_container_id=1 name_from=contents background_color=&FFFFFFFF color=&FF000000 name=some more text value= display=block font_size=16 child_ids=17
      id=17 inlineTextBox (0, 0)-(126, 19) offset_container_id=16 name_from=contents color=&FF000000 name=some more text value= character_offsets=8,18,34,44,49,64,74,80,90,95,101,111,120,127 word_starts=0,5,10 word_ends=4,9,14
  id=6 paragraph READONLY (8, 78)-(1084, 19) offset_container_id=1 background_color=&FFFFFFFF color=&FF000000 value= display=block html_tag=p font_size=16 child_ids=18
    id=18 staticText READONLY (8, 78)-(87, 19) offset_container_id=1 name_from=contents background_color=&FFFFFFFF color=&FF000000 name=end of text value= display=block font_size=16 child_ids=19
      id=19 inlineTextBox (0, 0)-(87, 19) offset_container_id=18 name_from=contents color=&FF000000 name=end of text value= character_offsets=10,20,30,35,45,51,56,62,72,81,87 word_starts=0,4,7 word_ends=3,6,11

[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: layoutComplete on node id 1
AXTreeUpdate tree data: doctype=html loaded=true loading_progress=1 mimetype=text/html url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> focus_id=1 routing_id=2
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 663) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[8621:8621:1021/073732:INFO:CONSOLE(877)] "loaded liblouis Native Client instance", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVox2ChromeBackgroundScript.js (877)
[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: layoutComplete on node id 1
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 653) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: layoutComplete on node id 1
AXTreeUpdate tree data: doctype=html loaded=true loading_progress=1 mimetype=text/html url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> focus_id=1 sel_anchor_object_id=8 sel_anchor_offset=0 sel_anchor_affinity=downstream sel_focus_object_id=8 sel_focus_offset=1 sel_focus_affinity=downstream routing_id=2
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 653) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: textSelectionChanged on node id 1
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 653) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: documentSelectionChanged on node id 1
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 653) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[1:1:1021/073732:INFO:render_accessibility_impl.cc(366)] Accessibility event: layoutComplete on node id 1
AXTreeUpdate: root id 1
id=1 rootWebArea FOCUSABLE READONLY (0, 0)-(1100, 647) background_color=&FFFFFFFF color=&FF000000 scroll_x=0 scroll_y=0 scroll_x_min=0 scroll_y_min=0 scroll_x_max=0 scroll_y_max=0 value= font-family=Tinos url=data:text/html,<!doctype html><span>start</span> <a href="google.com">google home page</a> <p>some more text</p> <p>end of text</p> html_tag=#document font_size=16 child_ids=4,5,6

[8621:8621:1021/073732:INFO:CONSOLE(2045)] "Starting ChromeVox.", source: chrome-extension://mndnfokpggljbaajbnioimlmbfngpief/chromeVoxChromePageScript.js (2045)
../../chrome/test/base/extension_js_browser_test.cc:64: Failure
Failed
Failed: RUN_TEST_F("CursorsTest","SingleDocSelection")
AssertionError: expected { Object () } to equal { Object () }
    at Function.assert.strictEqual (cursors_test.extjs:2905:32)
    at assertEquals (cursors_test.extjs:7396:17)
    at CursorsTest.verifySel (cursors_test.extjs:8963:9)
    at CursorsTest.<anonymous> (cursors_test.extjs:8593:16)
    at CallbackHelper.<anonymous> (cursors_test.extjs:8369:16)
    at CallFunctionAction.invoke (cursors_test.extjs:7861:24)
    at RunAllAction.invoke (cursors_test.extjs:8022:37)
    at Object.callback (cursors_test.extjs:8379:14)
    at Object.fireEventListeners_ (extensions::automationNode:514:22)
    at Object.dispatchEventAtTargeting_ (extensions::automationNode:484:10)
gen/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors_test-gen.cc:277: Failure
Value of: RunJavascriptTestF( true, "CursorsTest", "SingleDocSelection")
  Actual: false
Expected: true
[8621:8621:1021/073732:WARNING:url_request_context_getter.cc(43)] URLRequestContextGetter leaking due to no owning thread.
[  FAILED  ] CursorsTest.SingleDocSelection, where TypeParam =  and GetParam() =  (3016 ms)