go/misc/chrome/gophertool
..
background.html
background.js
gopher.js
gopher.png
manifest.json
popup.html
popup.js
README.txt

To install:

1) chrome://extensions/
2) click "[+] Developer Mode" in top right
3) "Load unpacked extension..."
4) pick $GOROOT/misc/chrome/gophertool

Done.  It'll now auto-reload from source.