I got it working now after updating the browser. As it turned out, Google Cloud Console changed, and the runtime image flashed to SD card from the AIY site is obsolete, which still has the version 61 of the Chromuim borwser (while the latest is 64 now).
So for those of you who just started the AIY project with Voice Kit, if you run into the same problem as me getting into the GCP Console page from your RPi browers, you need to update your Chromuim borwser on RPi. To do that, following these steps:
1) Go to this page:
https://packages.debian.org/stretch/chromium and go to the bottom of the page, and select the ARM version download link (the 3rd one in the list), and on that page, download the package from the security.debian.org/debian-security link on the ARM download page, which should download the chromium_63.0.3239.84-1~deb9u1_armhf.deb pack to your RPi3 device.
2) Since the packet name is too long, just rename it to something short, like Chrome.deb
3) Move it from the download folder to the Pi folder, and run the following command: sudo apt install -f
This should unpack the package, resolve the dependencies, and ge the new Chromuim borwser installed on your RPi3, and then, you can successfully log into the GCP Console, by going to console.cloud.google.com, without seeing the security blocking error.
Good luck!
Bill