https://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=org.chromium.chrome.browser.tabmodel.UndoTabModelTest%23testSaveStateCommitsUndos&testType=chrome_public_test_apk

Pretty sure the failure mode here is the same DCHECK failure as https://bugs.chromium.org/p/chromium/issues/detail?id=635730:

I   33.410s Main  pid: 13306, tid: 13306, name: chromium.chrome  >>> org.chromium.chrome <<<
I   33.410s Main  signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
I   33.410s Main  [FATAL:render_widget_host_view_android.cc(544)] Check failed: locks_on_frame_count_ > 0u (0 vs. 0)

(from https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%20Tester/builds/5017)

example is M, but this is occurring on K (e.g. https://build.chromium.org/p/chromium.android/builders/KitKat%20Tablet%20Tester/builds/5071) and L (e.g. https://build.chromium.org/p/chromium.android/builders/Lollipop%20Tablet%20Tester/builds/4321), too