Automated CTS run started for N:
https://wmatrix.googleplex.com/platform/unfiltered?platforms=reef&suites=arc-cts&days_back=15&releases=tot&hide_missing=True
but is sometimes suffering from even starting.

It's failing to Chrome OS login, so it doesn't look specific to ARC.
One cause is  Bug 697094 , and the other is this failure pattern I'm now filing. An instance is:

https://wmatrix.googleplex.com/testrun/unfiltered?test_ids=448060923
> Test logs > `cd ..` > cheets_CTS_N.CtsSystemUiTestCases.tgz > cheets_CTSHelper/sysinfo/var/log/messages

or
https://wmatrix.googleplex.com/testrun/unfiltered?test_ids=448049211

2017-03-12T03:03:33.177269-07:00 INFO session_manager[9374]: [INFO:browser_job.cc(140)] Running child /opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=25.0.0.127 --ui-prioritize-in-gpu-process --use-gl=egl --gpu-sandbox-failures-fatal=yes --arc-availability=officially-supported --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --system-developer-mode --login-profile=user --has-chromeos-keyboard --enable-touchview --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/default_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/default_small.jpg --child-wallpaper-large=/usr/share/chromeos-assets/wallpaper/child_large.jpg --child-wallpaper-small=/usr/share/chromeos-assets/wallpaper/child_small.jpg --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-prefixed-encrypted-media --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-manager --vmodule=screen_locker=2,webui_screen_locker=2,lock_state_controller=2,webui_login_view=2,power_button_observer=2,*/ui/display/manager/chromeos/*=1,*/ui/ozone/*=1,*zygote*=1,*plugin*=2,auto_enrollment_controller=1,*chromeos/login/*=1,*arc/*=1 
2017-03-12T03:03:33.415848-07:00 ERR kernel: [  610.717354] BUG: sleeping function called from invalid context at /mnt/host/source/src/third_party/kernel/v4.4/fs/dcache.c:754
2017-03-12T03:03:33.415887-07:00 ERR kernel: [  610.717368] in_atomic(): 0, irqs_disabled(): 0, pid: 3620, name: MountThread
2017-03-12T03:03:33.415891-07:00 WARNING kernel: [  610.717378] CPU: 1 PID: 3620 Comm: MountThread Tainted: G     U          4.4.52-07400-g15b52ca #1
2017-03-12T03:03:33.415892-07:00 WARNING kernel: [  610.717383] Hardware name: Google Reef/Reef, BIOS Google_Reef.9042.50.0 02/16/2017
2017-03-12T03:03:33.415895-07:00 WARNING kernel: [  610.717390]  0000000000000286 00000000538125c8 ffff880166ac3be0 ffffffff8aa927ee
2017-03-12T03:03:33.415896-07:00 WARNING kernel: [  610.717403]  0000000000000e24 ffff880168817000 ffff880166ac3c00 ffffffff8a88b553
2017-03-12T03:03:33.415899-07:00 WARNING kernel: [  610.717416]  ffffffff8b1c04a0 00000000000002f2 ffff880166ac3c28 ffffffff8a88b5f7
2017-03-12T03:03:33.415900-07:00 WARNING kernel: [  610.717428] Call Trace:
2017-03-12T03:03:33.415903-07:00 WARNING kernel: [  610.717444]  [<ffffffff8aa927ee>] dump_stack+0x4d/0x63
2017-03-12T03:03:33.415905-07:00 WARNING kernel: [  610.717455]  [<ffffffff8a88b553>] ___might_sleep+0x149/0x14e
2017-03-12T03:03:33.415907-07:00 WARNING kernel: [  610.717463]  [<ffffffff8a88b5f7>] __might_sleep+0x9f/0xa6
2017-03-12T03:03:33.415909-07:00 WARNING kernel: [  610.717472]  [<ffffffff8a9775f5>] dput+0x2f/0x206
2017-03-12T03:03:33.415911-07:00 WARNING kernel: [  610.717482]  [<ffffffff8aa09584>] ext4_d_revalidate+0x6e/0x97
2017-03-12T03:03:33.415913-07:00 WARNING kernel: [  610.717489]  [<ffffffff8a96f2dd>] lookup_fast+0xb5/0x296
2017-03-12T03:03:33.415915-07:00 WARNING kernel: [  610.717496]  [<ffffffff8a9703ff>] path_openat+0x2b0/0xc56
2017-03-12T03:03:33.415917-07:00 WARNING kernel: [  610.717504]  [<ffffffff8aa0a0ab>] ? ext4_free_crypt_info+0x3b/0x3e
2017-03-12T03:03:33.415919-07:00 WARNING kernel: [  610.717512]  [<ffffffff8aa0a4bc>] ? _ext4_get_encryption_info+0x3d7/0x416
2017-03-12T03:03:33.415921-07:00 WARNING kernel: [  610.717520]  [<ffffffff8a972b1a>] do_filp_open+0x5c/0xc6
2017-03-12T03:03:33.415922-07:00 WARNING kernel: [  610.717530]  [<ffffffff8a956c78>] ? slab_pre_alloc_hook+0x29/0x2f
2017-03-12T03:03:33.415924-07:00 WARNING kernel: [  610.717540]  [<ffffffff8af0033c>] ? _raw_spin_unlock+0xe/0x20
2017-03-12T03:03:33.415926-07:00 WARNING kernel: [  610.717550]  [<ffffffff8a963d32>] do_sys_open+0x86/0x198
2017-03-12T03:03:33.415928-07:00 WARNING kernel: [  610.717557]  [<ffffffff8a963d32>] ? do_sys_open+0x86/0x198
2017-03-12T03:03:33.415930-07:00 WARNING kernel: [  610.717565]  [<ffffffff8a963e62>] SyS_open+0x1e/0x20
2017-03-12T03:03:33.415932-07:00 WARNING kernel: [  610.717573]  [<ffffffff8af00761>] entry_SYSCALL_64_fastpath+0x1c/0x74
2017-03-12T03:03:33.646041-07:00 INFO session_manager[9374]: [INFO:browser_job.cc(149)] Terminating process group: Restarting browser on-demand.
2017-03-12T03:03:33.646067-07:00 INFO session_manager[9374]: [INFO:system_utils_impl.cc(110)] Sending 9 to -9391 as 1000
2017-03-12T03:03:33.655341-07:00 INFO session_manager[9374]: [INFO:child_exit_handler.cc(77)] Handling 9391 exit.
2017-03-12T03:03:33.655507-07:00 ERR session_manager[9374]: [ERROR:child_exit_handler.cc(85)]   Exited with signal 9
2017-03-12T03:03:33.655585-07:00 INFO session_manager[9374]: [INFO:session_manager_service.cc(274)] Exiting process is chrome.
2017-03-12T03:03:33.655652-07:00 INFO session_manager[9374]: [INFO:browser_job.cc(149)] Terminating process group: Ensuring browser processes are gone.
2017-03-12T03:03:33.655771-07:00 INFO session_manager[9374]: [INFO:system_utils_impl.cc(110)] Sending 9 to -9391 as 1000
2017-03-12T03:03:33.656368-07:00 INFO session_manager[9374]: [INFO:browser_job.cc(140)] Running child /opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=25.0.0.127 --ui-prioritize-in-gpu-process --use-gl=egl --gpu-sandbox-failures-fatal=yes --arc-availability=officially-supported --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --system-developer-mode --login-profile=user --has-chromeos-keyboard --enable-touchview --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/default_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/default_small.jpg --child-wallpaper-large=/usr/share/chromeos-assets/wallpaper/child_large.jpg --child-wallpaper-small=/usr/share/chromeos-assets/wallpaper/child_small.jpg --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-prefixed-encrypted-media --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-manager --disable-arc-opt-in-verification --enable-net-benchmarking --metrics-recording-only --no-default-browser-check --no-first-run --enable-gpu-benchmarking --disable-background-networking --disable-component-extensions-with-background-pages --disable-default-apps --disable-search-geolocation-disclosure --enable-smooth-scrolling --enable-threaded-compositing --remote-debugging-port=57915 --start-maximized --ash-disable-system-sounds --allow-failed-policy-fetch-for-test --oobe-skip-postlogin --disable-gaia-services --testing-channel=NamedTestingInterface:/tmp/.org.chromium.Chromium.BfelkG/.org.chromium.Chromium.SXNOUt --vmodule=screen_locker=2,webui_screen_locker=2,lock_state_controller=2,webui_login_view=2,power_button_observer=2,*/ui/display/manager/chromeos/*=1,*/ui/ozone/*=1,*zygote*=1,*plugin*=2,auto_enrollment_controller=1,*chromeos/login/*=1,*arc/*=1,*/chromeos/net/*=2,*/chromeos/login/*=2,chrome_browser_main_posix=2 
2017-03-12T03:03:33.725314-07:00 ERR mtpd[2151]: LIBMTP_Detect_Raw_Devices failed with 5
2017-03-12T03:03:33.727677-07:00 ERR mtpd[2151]: message repeated 5 times: [ LIBMTP_Detect_Raw_Devices failed with 5]
2017-03-12T03:03:37.767598-07:00 WARNING cryptohomed[3561]: Could not load the device policy file.
2017-03-12T03:03:37.781693-07:00 ERR kernel: [  615.082611] i2c_designware i2c_designware.2: i2c_dw_handle_tx_abort: slave address not acknowledged (7bit mode)
2017-03-12T03:03:37.816260-07:00 WARNING cryptohomed[3561]: Could not load the device policy file.
2017-03-12T03:03:37.876515-07:00 WARNING cryptohomed[3561]: No valid keysets on disk for c513faa442802a92dfe650ea1a90c302f1ee39c2
2017-03-12T03:03:37.876547-07:00 ERR cryptohomed[3561]: Failed to decrypt any keysets for c513faa442802a92dfe650ea1a90c302f1ee39c2
2017-03-12T03:03:37.876562-07:00 ERR cryptohomed[3561]: Error, cryptohome must be re-created because of fatal error.
2017-03-12T03:03:37.877738-07:00 ERR kernel: [  615.178476] BUG: sleeping function called from invalid context at /mnt/host/source/src/third_party/kernel/v4.4/fs/dcache.c:754
2017-03-12T03:03:37.877761-07:00 ERR kernel: [  615.178484] in_atomic(): 0, irqs_disabled(): 0, pid: 3620, name: MountThread
2017-03-12T03:03:37.877762-07:00 WARNING kernel: [  615.178489] CPU: 0 PID: 3620 Comm: MountThread Tainted: G     U          4.4.52-07400-g15b52ca #1
2017-03-12T03:03:37.877763-07:00 WARNING kernel: [  615.178492] Hardware name: Google Reef/Reef, BIOS Google_Reef.9042.50.0 02/16/2017
2017-03-12T03:03:37.877764-07:00 WARNING kernel: [  615.178495]  0000000000000286 00000000538125c8 ffff880166ac3b78 ffffffff8aa927ee
2017-03-12T03:03:37.877765-07:00 WARNING kernel: [  615.178502]  0000000000000e24 ffff880168817000 ffff880166ac3b98 ffffffff8a88b553
2017-03-12T03:03:37.877766-07:00 WARNING kernel: [  615.178508]  ffffffff8b1c04a0 00000000000002f2 ffff880166ac3bc0 ffffffff8a88b5f7
2017-03-12T03:03:37.877767-07:00 WARNING kernel: [  615.178514] Call Trace:
2017-03-12T03:03:37.877768-07:00 WARNING kernel: [  615.178524]  [<ffffffff8aa927ee>] dump_stack+0x4d/0x63
2017-03-12T03:03:37.877769-07:00 WARNING kernel: [  615.178530]  [<ffffffff8a88b553>] ___might_sleep+0x149/0x14e
2017-03-12T03:03:37.877770-07:00 WARNING kernel: [  615.178533]  [<ffffffff8a88b5f7>] __might_sleep+0x9f/0xa6
2017-03-12T03:03:37.877771-07:00 WARNING kernel: [  615.178539]  [<ffffffff8a9775f5>] dput+0x2f/0x206
2017-03-12T03:03:37.877771-07:00 WARNING kernel: [  615.178543]  [<ffffffff8aa09584>] ext4_d_revalidate+0x6e/0x97
2017-03-12T03:03:37.877772-07:00 WARNING kernel: [  615.178547]  [<ffffffff8a96f2dd>] lookup_fast+0xb5/0x296
2017-03-12T03:03:37.877773-07:00 WARNING kernel: [  615.178550]  [<ffffffff8a96f894>] walk_component+0x5f/0x179
2017-03-12T03:03:37.877774-07:00 WARNING kernel: [  615.178553]  [<ffffffff8a96ff0f>] path_lookupat+0x82/0x103
2017-03-12T03:03:37.877775-07:00 WARNING kernel: [  615.178557]  [<ffffffff8a97174b>] filename_lookup+0x8c/0x11d
2017-03-12T03:03:37.877775-07:00 WARNING kernel: [  615.178562]  [<ffffffff8a956c78>] ? slab_pre_alloc_hook+0x29/0x2f
2017-03-12T03:03:37.877776-07:00 WARNING kernel: [  615.178566]  [<ffffffff8a9588ce>] ? kmem_cache_alloc+0x24/0x123
2017-03-12T03:03:37.877777-07:00 WARNING kernel: [  615.178569]  [<ffffffff8a97142c>] ? getname_flags+0x3d/0x194
2017-03-12T03:03:37.877778-07:00 WARNING kernel: [  615.178572]  [<ffffffff8a971568>] ? getname_flags+0x179/0x194
2017-03-12T03:03:37.877779-07:00 WARNING kernel: [  615.178575]  [<ffffffff8a9718aa>] user_path_at_empty+0x37/0x3d
2017-03-12T03:03:37.877779-07:00 WARNING kernel: [  615.178578]  [<ffffffff8a9718aa>] ? user_path_at_empty+0x37/0x3d
2017-03-12T03:03:37.877780-07:00 WARNING kernel: [  615.178582]  [<ffffffff8a968e32>] vfs_fstatat+0x60/0xaf
2017-03-12T03:03:37.877781-07:00 WARNING kernel: [  615.178586]  [<ffffffff8a968f5e>] vfs_lstat+0x1e/0x20
2017-03-12T03:03:37.877782-07:00 WARNING kernel: [  615.178589]  [<ffffffff8a968fd5>] SYSC_newlstat+0x24/0x51
2017-03-12T03:03:37.877783-07:00 WARNING kernel: [  615.178593]  [<ffffffff8a94066b>] ? __might_fault+0x35/0x37
2017-03-12T03:03:37.877783-07:00 WARNING kernel: [  615.178597]  [<ffffffff8a974b22>] ? SyS_getdents+0xeb/0x117
2017-03-12T03:03:37.877784-07:00 WARNING kernel: [  615.178600]  [<ffffffff8a974884>] ? iterate_dir+0x115/0x115
2017-03-12T03:03:37.877785-07:00 WARNING kernel: [  615.178603]  [<ffffffff8a9690a1>] SyS_newlstat+0xe/0x10
2017-03-12T03:03:37.877786-07:00 WARNING kernel: [  615.178609]  [<ffffffff8af00761>] entry_SYSCALL_64_fastpath+0x1c/0x74
2017-03-12T03:03:37.912472-07:00 ERR cryptohomed[3561]: Fatal decryption error, but unable to remove cryptohome.
2017-03-12T03:03:37.914999-07:00 WARNING cryptohomed[3561]: PKCS#11 initialization requested but cryptohome is not mounted.