SDCH
SDCH is a data compression algorithm created by Google, based on VCDIFF.
SDCH achieves its effectiveness by using pre-negotiated dictionaries to "warm up" its internal state prior to encoding or decoding. These may either be already stored locally, or uploaded from a source and then cached.
It was supported natively in Google Chrome, Chromium, and Android, as well as on Google websites.
SDCH compression was removed from Google Chrome, and other Chromium products, in version 59.
