Include a separate “metered network” property in addition to “save data”

[thetorpedodog]

Because OSs conceptually separate “metered network” from “data saver”, it is still worth including both of those two properties as available settings.

• Windows 10 supports marking networks as metered
• Recent Android versions detect networks that advertise themselves as metered networks, allow users to mark networks as metered manually, and recommends developers detect metered networks in conjunction with Data Saver to save data.

This was originally opened as #41, but the author closed the issue themselves. Please feel free to move discussion back to that issue if it would be better.

[Jaifroid]

The fragmentation of the Network Information API is a real shame. This is still an important issue for users -- especially, but not only, outside of the privileged world. In 2023 there is still no way to detect reliably whether the user is on a metered network. Windows still has its own "metered network" option that users can set manually for their connections, but the Network Information API doesn't know about it and the saveData property is undefined on Windows. On Android, the saveData property may be defined (?), but it's not very clear on what basis it gets set. So developers ignore the API completely, for the most part.

A reliable "metered" property that works across Android and Windows at least in Chromium browsers (probably no hope of getting Apple on board) would be very welcome.