I downloaded the Auto Refresh Plus Chrome plugin, set it to auto-refresh the 16GB page (https://play.google.com/store/devices/details?id=nexus_4_16g...) every 1s and set the "Popup notification once FIND the target" option using the word "STOCK".

I went through 3-4 false starts of trying to add it to cart and having it fail, but it eventually succeeded and I was able to add to cart and complete the purchase at 3:04pm EST.