At least on linux they all seem to be failing:

"""
@@@STEP_WARNINGS@@@
WARNING: suspected flake, retrying test!

ENV: PYTHONDONTWRITEBYTECODE=1 BUILDBOT_BUILDERNAME=linux-sdk-multi LOGNAME=chrome-bot USER=chrome-bot HOME=/home/chrome-bot PATH=/home/chrome-bot/slavebin:/mnt/data/b/depot_tools:/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin PYTHONUNBUFFERED=1 BUILDBOT_BUILDBOTURL=http://build.chromium.org/p/client.nacl.sdk/ DISPLAY=:99 LANG=en_US.UTF-8 BUILDBOT_BLAMELIST=[] SHELL=/bin/bash XAUTHORITY=/tmp/xvfb-run.jqrVhh/Xauthority CHROME_DEVEL_SANDBOX=/opt/chromium/chrome_sandbox BUILDBOT_MASTERNAME=client.nacl.sdk NACL_ENABLE_PPAPI_DEV=1 BUILDBOT_GOT_REVISION=None PYTHONPATH= BUILDBOT_SCHEDULER=None BUILDBOT_REVISION= CHROME_HEADLESS=1 BUILDBOT_BRANCH= GIT_USER_AGENT=linux2 git/2.9.3 vm145-m3.golo.chromium.org BUILDBOT_BUILDNUMBER=13583 PWD=/mnt/data/b/build/slave/sdk/build/src/native_client_sdk/src/build_tools BUILDBOT_SLAVENAME=vm145-m3 BUILDBOT_CLOBBER= PAGER=cat
LAUNCHING: /mnt/data/b/build/slave/sdk/build/src/out/Release/chrome --enable-logging --disable-web-resources --disable-features=NetworkPrediction --disable-sync --no-first-run --no-default-browser-check --log-level=1 --safebrowsing-disable-auto-update --disable-default-apps --metrics-recording-only --explicitly-allowed-ports=44952 --user-data-dir=/tmp/browserprofile_dD6jmE --log-net-log=/tmp/browserprofile_dD6jmE/netlog.json --use-gl=osmesa --register-pepper-plugins=/mnt/data/b/build/slave/sdk/build/src/out/pepper_55/examples/api/network_monitor/linux/Debug/network_monitor.so;application/x-ppapi-debug --no-sandbox --allow-nacl-socket-api=192.168.131.145 --unlimited-storage --disable-component-update http://192.168.131.145:44952/index.html?tc=linux&config=Debug&test=true
I'M THE SESSION LEADER!
PID 29423
Xlib:  extension "RANDR" missing on display ":99".
Xlib:  extension "RANDR" missing on display ":99".

(chrome:29423): GConf-WARNING **: Client failed to connect to the D-BUS daemon:
Failed to connect to socket /tmp/dbus-FQXvQOH4JE: Connection refused

(chrome:29423): LIBDBUSMENU-GLIB-WARNING **: Unable to get session bus: Could not connect: Connection refused
[29459:29459:0913/170538:ERROR:gl_implementation.cc(223)] Failed to load /mnt/data/b/build/slave/sdk/build/src/out/Release/libosmesa.so: /mnt/data/b/build/slave/sdk/build/src/out/Release/libosmesa.so: cannot open shared object file: No such file or directory
[29459:29459:0913/170538:ERROR:gpu_child_thread.cc(331)] Exiting GPU process due to errors during initialization
[29423:29440:0913/170538:ERROR:browser_gpu_channel_host_factory.cc(113)] Failed to launch GPU process.
[   201 ms] |||| GET /index.html?tc=linux&config=Debug&test=true (/index.html)
[   206 ms] |||| GET /common.js (/common.js)
[   207 ms] |||| GET /example.js (/example.js)
[   239 ms] |||| GET /test.js (/test.js)
[29423:29423:0913/170538:ERROR:interface_registry.cc(99)] Failed to locate a binder for interface: dom_distiller::mojom::DistillabilityService
[   244 ms] |||| GET /nacltest.js (/nacltest.js)
[   259 ms] |||| [STARTUP]
[   270 ms] |||| GET /favicon.ico (/favicon.ico)
[29423:29423:0913/170538:ERROR:interface_registry.cc(99)] Failed to locate a binder for interface: dom_distiller::mojom::DistillabilityService
[ 40324 ms] |||| 
[ 40324 ms] |||| [CLIENT_ERROR] nacl_module / nacl_module did not load. Status: OPENED / undefined
[ 40326 ms] |||| 
[ 40328 ms] |||| A nexe load error occured, aborting testing.
[ 40330 ms] |||| 
[ 40333 ms] |||| [SHUTDOWN] 0 passed, 0 failed, 1 errors
##################### Terminating the browser
[29423:29423:0913/170618:ERROR:zygote_communication_linux.cc(292)] Failed to send GetTerminationStatus message to zygote

WARNING: failed too many times, not retrying.

[  FAILED  ] network_monitor.linux_debug_test (245377 ms)

"""