[gsvelto]

Detecting low memory scenarios is surprisingly hard on desktop operating systems, but trivially simple on Android/iOS. Firefox for Android already made extensive use of this feature while desktop Firefox' available memory watcher underwent a lot of changes over the years before becoming fairly reliable.

[iggldiggl]

Though unfortunately especially on Android some vendors are overly aggressive in signalling memory pressure, so while the API might be easier to use, the practical result still isn't really good, either, because now instead tabs get unloaded too often. (And the move to multi-process on Android has the unfortunate side-effect that a too-aggressive system OOM killer can now pick out individual content processes and randomly kill tabs without regards to any priority as to which tabs should be unloaded first.)