HTTP
HTTPS





Notes:

USB Implemented behind the experimental flag chrome://flags/#enable-experimental-web-platform-features.
Encrypted Media (EME) May succeed without permission depending on the implementation.
Attempts to use known key systems. (See the source for the list of supported key systems.)
Persistent Storage Implemented behind the experimental flag chrome://flags/#enable-experimental-web-platform-features. In Chrome, granted based on user agent heuristics (e.g. "is site bookmarked?"); no permission prompt. (spec)
On GitHub