Before doing bug 1474130, I would like to rewrite the js modules which are used in ContentSessionStore.jsm. In this bug, I will focus on DocShellCapabilities.jsm and ScrollPosition.jsm.

Small wishlist item: It would be nice if the resolution saving code used on mobile [1][2] could be integrated into this as well. But since that currently isn't part of ScrollPosition.jsm and Desktop currently doesn't do pinch zooming, either, feel free to ignore my request for now. [1] https://dxr.mozilla.org/mozilla-central/rev/90853a59691e0c77014c38049bfb38b2b6ca1e16/mobile/android/components/SessionStore.js#938-947 [2] https://dxr.mozilla.org/mozilla-central/rev/90853a59691e0c77014c38049bfb38b2b6ca1e16/mobile/android/chrome/geckoview/GeckoViewContent.js#91-108

Actively being worked on, so triaged as P1.

Get rid of DocShellCapabilities.jsm and ScrollPosition.jsm

Try looks fine. part 1. https://treeherder.mozilla.org/#/jobs?repo=try&revision=3b23f33fc72e627f5a376f9e65756b35a57cda2a&selectedJob=207016542 part 2. https://treeherder.mozilla.org/#/jobs?repo=try&revision=7bbf7eadfd2307744b366b23247c12ca5962ab53&selectedJob=207008358

Pushed by ebalazs@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/5b7afb9ada5e Rewrite DocShellCapabilities.jsm and ScrollPosition.jsm into C++ r=nika https://hg.mozilla.org/integration/autoland/rev/50d03049245a part 2 - Get rid of ScrollPosition.jsm r=JanH,nika

https://hg.mozilla.org/mozilla-central/rev/5b7afb9ada5e https://hg.mozilla.org/mozilla-central/rev/50d03049245a