This is a browser extension that plays the Wii Shop Channel theme in the background when you visit a shopping website. You can also select the music from the 3DS eShop, DSi Shop, Wii Shop Banner/Home, Wii U eShop, Mii Channel (Wii or 3DS), Coconut Mall, and the "Wii Shop Wednesday" song from Nirvana The Band The Show.
The extension only requires two permissions: Tabs, to check the URL of the currently-active tab, and Notifications, to show a message after the extension is installed.
This extension is not developed by, or affiliated with, Nintendo in any way. The rights for all included music belongs to Nintendo, with the exception of "Wii Shop Wednesday", which is from Nirvana The Band The Show.