This appears to be responsible for the majority of chrome_public_test_apk failures on https://ci.chromium.org/p/chromium/builders/luci.chromium.try/android-kitkat-arm-rel?limit=200

Looks to be hitting a DCHECK:
F chromium: [FATAL:unguessable_token.h(67)] Check failed: !is_empty().

From https://luci-logdog.appspot.com/logs/chromium/android/swarming/logcats/4146941c7f142411/+/logcat_logcat_org.chromium.chrome.browser.video.FullscreenVideoTest.testFullscreenDimensions_20181119T210658-UTC_097f1a0b0189b2c0

Looking at https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=chrome_public_test_apk&showAllRuns=true&tests=org.chromium.chrome.browser.video.FullscreenVideoTest%23testFullscreenDimensions

https://chromium-review.googlesource.com/c/chromium/src/+/1336438/9 is the first CL that exhibited this flakiness on the CQ. That CL also shows up in the blamelist the first time one of the CI bots failed the test:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Marshmallow%2064%20bit%20Tester/24934

Could be another CL on the list, but +the author in case.

jonross@ hope this helps: crash trace from KitKat:

I/MediaFocusControl(  751):  AudioFocus  abandonAudioFocus() from android.media.AudioManager@4286b970org.chromium.content.browser.AudioFocusDelegate@426aac08
F/chromium(11549): [FATAL:intersection_geometry.cc(172)] Check failed: frame_view->ShouldThrottleRendering() || !layout_view || !(layout_view->NeedsPaintPropertyUpdate() || layout_view->DescendantNeedsPaintPropertyUpdate()). 
F/chromium(11549): #00 0x75b84d7b /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000e2d7b
F/chromium(11549): #01 0x7be37fd1 /data/app-lib/org.chromium.chrome.tests-1/libblink_core.cr.so+0x00c7dfd1
F/chromium(11549): #02 0x7be382ab /data/app-lib/org.chromium.chrome.tests-1/libblink_core.cr.so+0x00c7e2ab
F/chromium(11549): #03 0x7bda440f /data/app-lib/org.chromium.chrome.tests-1/libblink_core.cr.so+0x00bea40f
F/chromium(11549): #04 0x7ad90e27 /data/app-lib/org.chromium.chrome.tests-1/libblink_platform.cr.so+0x00499e27
F/chromium(11549): #05 0x7acbbe71 /data/app-lib/org.chromium.chrome.tests-1/libblink_platform.cr.so+0x003c4e71
F/chromium(11549): #06 0x7ad14ae3 /data/app-lib/org.chromium.chrome.tests-1/libblink_platform.cr.so+0x0041dae3
F/chromium(11549): #07 0x75b6fd15 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000cdd15
F/chromium(11549): #08 0x75b78eed /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000d6eed
F/chromium(11549): #09 0x75bb7d89 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x00115d89
F/chromium(11549): #10 0x75b6fd15 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000cdd15
F/chromium(11549): #11 0x75b78eed /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000d6eed
F/chromium(11549): #12 0x75b8b847 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000e9847
F/chromium(11549): #13 0x75b8ba05 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000e9a05
F/chromium(11549): #14 0x75b8bdb9 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000e9db9
F/chromium(11549): #15 0x75b8d169 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000eb169
F/chromium(11549): #16 0x75b8b655 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000e9655
F/chromium(11549): #17 0x75ba0d07 /data/app-lib/org.chromium.chrome.tests-1/libbase.cr.so+0x000fed07
F/chromium(11549): #18 0x7f40718d /data/app-lib/org.chromium.chrome.tests-1/libcontent.cr.so+0x00f9d18d
F/chromium(11549): #19 0x7f48106b /data/app-lib/org.chromium.chrome.tests-1/libcontent.cr.so+0x0101706b
F/chromium(11549): #20 0x7d6b7871 /data/app-lib/org.chromium.chrome.tests-1/libembedder.cr.so+0x0000c871
F/chromium(11549): #21 0x7f480869 /data/app-lib/org.chromium.chrome.tests-1/libcontent.cr.so+0x01016869
F/chromium(11549): #22 0x4158070f /system/lib/libdvm.so+0x0001e70f
F/chromium(11549): #23 0x415b0c65 /system/lib/libdvm.so+0x0004ec65
F/chromium(11549): #24 0x41589b23 /system/lib/libdvm.so+0x00027b23
F/chromium(11549): #25 0x41590ae3 /system/lib/libdvm.so+0x0002eae3
F/chromium(11549): #26 0x4158e17b /system/lib/libdvm.so+0x0002c17b
F/chromium(11549): #27 0x415c30bf /system/lib/libdvm.so+0x000610bf
F/chromium(11549): #28 0x415c30e3 /system/lib/libdvm.so+0x000610e3
F/chromium(11549): #29 0x415b7dc9 /system/lib/libdvm.so+0x00055dc9
F/chromium(11549): #30 0x4010616b /system/lib/libc.so+0x0000d16b
F/chromium(11549): #31 0x40106303 /system/lib/libc.so+0x0000d303
F/libc    (11549): Fatal signal 6 (SIGABRT) at 0x00002d1d (code=-6), thread 11563 (CrRendererMain)
D/dalvikvm(11677): Added shared lib /data/data/com.google.android.apps.chrome/incremental-install-files/lib/libblink_modules.cr.so 0x4268abf0
D/dalvikvm(11677): No JNI_OnLoad found in /data/data/com.google.android.apps.chrome/incremental-install-files/lib/libblink_modules.cr.so 0x4268abf0, skipping init
D/dalvikvm(11677): Trying to load lib /data/data/com.google.android.apps.chrome/incremental-install-files/lib/libmedia_blink.cr.so 0x4268abf0
I/DEBUG   (  177): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG   (  177): Build fingerprint: 'google/hammerhead/hammerhead:4.4.4/KTU85H/4218096:userdebug/dev-keys'

org.chromium.chrome.browser.video.FullscreenVideoTest#testFullscreenDimensions is flaky.

Findit has detected 19 new flake occurrences of this test. List
of all flake occurrences can be found at:
https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyeQsSBUZsYWtlIm5jaHJvbWl1bUBjaHJvbWVfcHVibGljX3Rlc3RfYXBrQG9yZy5jaHJvbWl1bS5jaHJvbWUuYnJvd3Nlci52aWRlby5GdWxsc2NyZWVuVmlkZW9UZXN0I3Rlc3RGdWxsc2NyZWVuRGltZW5zaW9ucww.

Since this test is still flaky, this issue has been moved back onto the Sheriff
Bug Queue if it's not already there.

If the result above is wrong, please file a bug using this link:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Detection%20-%20Wrong%20result%20for%20org.chromium.chrome.browser.video.FullscreenVideoTest#testFullscreenDimensions&comment=Link%20to%20flake%20occurrences%3A%20https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyeQsSBUZsYWtlIm5jaHJvbWl1bUBjaHJvbWVfcHVibGljX3Rlc3RfYXBrQG9yZy5jaHJvbWl1bS5jaHJvbWUuYnJvd3Nlci52aWRlby5GdWxsc2NyZWVuVmlkZW9UZXN0I3Rlc3RGdWxsc2NyZWVuRGltZW5zaW9ucww

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

It looks an owner is assigned. Let me remove Sheriff-Chromium label.

this is blocking rolls of chromium in ChromeForAndroid, going to disable the test

+peconn as someone knowledgeable about the test

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fbc976028bdf3dbadb46fea5b5a03192bc79455c

commit fbc976028bdf3dbadb46fea5b5a03192bc79455c
Author: Egor Pasko <pasko@chromium.org>
Date: Wed Nov 21 14:53:01 2018

Disable flaky FullscreenVideoTest#testFullscreenDimensions

TBR=peconn@chromium.org,dtrainor@chromium.org
NOTRY=true

Bug:  906840 
Change-Id: I3a9627c2095e71ffccc4f4b0a2e0371d73dc670a
Reviewed-on: https://chromium-review.googlesource.com/c/1346304
Commit-Queue: Egor Pasko <pasko@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610048}
[modify] https://crrev.com/fbc976028bdf3dbadb46fea5b5a03192bc79455c/chrome/android/javatests/src/org/chromium/chrome/browser/video/FullscreenVideoTest.java

org.chromium.chrome.browser.video.FullscreenVideoTest#testFullscreenDimensions is flaky.

Findit has detected 10 new flake occurrences of this test. List
of all flake occurrences can be found at:
https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyeQsSBUZsYWtlIm5jaHJvbWl1bUBjaHJvbWVfcHVibGljX3Rlc3RfYXBrQG9yZy5jaHJvbWl1bS5jaHJvbWUuYnJvd3Nlci52aWRlby5GdWxsc2NyZWVuVmlkZW9UZXN0I3Rlc3RGdWxsc2NyZWVuRGltZW5zaW9ucww.

Since this test is still flaky, this issue has been moved back onto the Sheriff
Bug Queue if it's not already there.

If the result above is wrong, please file a bug using this link:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Detection%20-%20Wrong%20result%20for%20org.chromium.chrome.browser.video.FullscreenVideoTest#testFullscreenDimensions&comment=Link%20to%20flake%20occurrences%3A%20https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyeQsSBUZsYWtlIm5jaHJvbWl1bUBjaHJvbWVfcHVibGljX3Rlc3RfYXBrQG9yZy5jaHJvbWl1bS5jaHJvbWUuYnJvd3Nlci52aWRlby5GdWxsc2NyZWVuVmlkZW9UZXN0I3Rlc3RGdWxsc2NyZWVuRGltZW5zaW9ucww

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

Chromium Sheriff here.
It looks an owner is assigned. Let me remove Sheriff-Chromium label.

+kylechar@ FYI OOP-D on Android

+ericrk FYI OOP-D on Android too

The test is disabled and an owner is assigned. Removing sheriff-android label.

I believe that this is the same root cause as 909903. For fix a fix is landing.

I'm running an experimental CL to try to confirm this supposition.

I'll look at re-enabling these after the suspected fix lands

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f91f92d36ee2dc2f7f21fbe3b84d9bafe3d655da

commit f91f92d36ee2dc2f7f21fbe3b84d9bafe3d655da
Author: jonross <jonross@chromium.org>
Date: Mon Dec 03 15:33:21 2018

Re-enable FullscreenVideoTest#testFullscreenDimensions

This test had been disabled due to flakiness. My change to frame eviction was
the likely cause. This was fixed by https://chromium-review.googlesource.com/c/chromium/src/+/1355845

I also separately ran an experiment which confirmed that the suspected mode of
failure occurs frequently during testing. Where currently visible surfaces are
being evicted. My change invalidated the current id, with the goal of allocating
new ids closer to usage. Unfortunately on Android the eviction process itself
can be the signal of needing a new id.

Now we simply allocate if visible.

TBR=peconn@chromium.org

Bug:  906840 
Change-Id: I917a2e230ee472a48858b56feca2c96dc7bd7761
Reviewed-on: https://chromium-review.googlesource.com/c/1358652
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613091}
[modify] https://crrev.com/f91f92d36ee2dc2f7f21fbe3b84d9bafe3d655da/chrome/android/javatests/src/org/chromium/chrome/browser/video/FullscreenVideoTest.java

The test looks stable now. Only failure I see on marshmallow was a timeout. The rest were all green.