[Suggestion] Add user agent switcher to the Steam Browser

[uzigone]

Your system information

• Steam client version: stable
• SteamOS version: stable
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

When I open the Steam Browser, the user agent of the browser is the Valve Steam Gamepad, which obviously has its quirks. The main issue that I have is that I cannot open Battlefield 3 in Gaming mode because it opens the server browser in an actual browser, in Gaming Mode that is the Steam Browser, and when I try to join a game it's telling me to run Windows. If I could just change the user agent of the Steam Browser to a Windows machine I'd get Battlefield 3 running without any issues (In Desktop mode the game runs perfect)

It should be fairly easy to implement because as far as I understand the Steam Browser runs on Chromium, and Chromium has a built in user agent switcher.

Steps for reproducing this issue:

1. Open Steam Browser
2. Check User Agent.