[nobodyorother]

The obvious solution is not having an ambient light sensor API, or a much more granular one, like the battery API should've been.

[0x00000000]

Exactly. Same with vibration, accelerometer, and gyro. For me personally there is zero reason why my browser should ever need these yet they can use them without any permission on Android Chrome and they cannot be disabled without rooting your phone.

[untog]

Games can use all three of those very effectively. Agree they should be behind a permission prompt, though.

[amluto]

Gyro is really nice for VR. But it should not be allowed in background tabs. No clue whether it is right now.