alt Hacker NewsI'm aware of a few things, myself:
1) Google properties
1a) Chromecast
2) a few web-based games that were really pushing the envelope on web APIs and didn't bother testing on Firefox
3) WebUSB, commonly used for some things like keyboard customization apps
Which Google properties are Chrome only? I'm not doubting you but the major ones (search, mail, maps, ads) are extremely cross-platform.