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

e.g. https://build.chromium.org/p/chromium.android/builders/Lollipop%20Tablet%20Tester/builds/4316

I *think* the crash is this DCHECK failure:

I   28.460s Main  pid: 16978, tid: 16978, name: chromium.chrome  >>> org.chromium.chrome <<<
I   28.460s Main  signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
I   28.460s Main  [FATAL:render_widget_host_view_android.cc(544)] Check failed: locks_on_frame_count_ > 0u (0 vs. 0)

this also appears on K (e.g. https://build.chromium.org/p/chromium.android/builders/KitKat%20Tablet%20Tester/builds/5072) and M (e.g. https://build.chromium.org/p/chromium.android/builders/Marshmallow%20Tablet%20Tester/builds/5013)