About DataSaver Proxy for Firefox
Google Data Saver is Proxy Service Provided by Google.Google DataSaver is extension available in Google Chrome which enable use of this service. Firefox didn't had the extension.So I ported the extension adding some new features.
When A HTTP web-request is made by browser,it is directed to google proxy server "googlezip.net" adding proxy-parameters.
All HTTPS requests are NOT directed to proxy server.They are bypassed and made Directedly.
Proxy Server is owned by Google.This Addon is NOT OFFICIAL Implementation of Google DataSaver Proxy.
You can read more about Compression at : https://developer.chrome.com/multidevice/data-compression
Version Released (v2.1)

Android Version of Google Data Saver Proxy Released