I've also filed a feedback comment on this.

I am experiencing a similar situation. After rebooting to apply Version 61.0.3136.5 (Official Build) dev (64-bit) on this HP ChromeBook 13 G1, the display flashes off and back on at roughly one second intervals at the login screen, and continues even after logged in.  When connected to a second monitor, the second monitor does not flash / blink. The unit was not blinking like this  applying the new version.

If I can provide any additional information, please let me know what would be helpful.

Platform
9672.0.0 (Official Build) dev-channel chell
Firmware
Google_Chell.7820.253.0
Channel
Currently on dev
CHANGE CHANNEL
ARC Version
4118168
Blink
537.36 (@)
V8
6.1.191
User Agent
Mozilla/5.0 (X11; CrOS x86_64 9672.0.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3136.5 Safari/537.36
Command Line
/opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=26.0.0.126 --ui-prioritize-in-gpu-process --use-gl=egl --enable-native-gpu-memory-buffers --gpu-sandbox-failures-fatal=yes --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --login-profile=user --has-chromeos-keyboard --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/oem_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/oem_small.jpg --default-wallpaper-is-oem --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-consumer-kiosk --arc-availability=officially-supported --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-manager --first-exec-after-boot --vmodule=*arc/*=1,*chromeos/login/*=1,auto_enrollment_controller=1,*plugin*=2,*zygote*=1,*/ui/ozone/*=1,*/ui/display/manager/chromeos/*=1,power_button_observer=2,webui_login_view=2,lock_state_controller=2,webui_screen_locker=2,screen_locker=2
Build Date
Wednesday, June 21, 2017

One more detail - the flashing on and off occurs before the login screen appears - the Chrome logo splash screen flashes a time or two.