This involves setting: browser.tabs.remote.warmup.enabled to true for Nightly builds.

Comment on attachment 8947168 [details] Bug 1423220 - Enable tab warming by default for Nightly builds. https://reviewboard.mozilla.org/r/216924/#review224822 Sorry for the delay, this trivial review request got lost in my backlog that I'm working through. Not much to review here, really.

Pushed by mconley@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/adf758d8cff9 Enable tab warming by default for Nightly builds. r=dao

Backout by csabou@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/5db3b0cf00bf Backed out changeset adf758d8cff9 for frequent mochitest browser chrome failures on dom/base/test/browser_bug1303838.js

Backed out changeset for frequent mochitest browser chrome failures on dom/base/test/browser_bug1303838.js Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&filter-resultStatus=testfailed&filter-resultStatus=busted&filter-resultStatus=exception&filter-searchStr=browser%20chrome&fromchange=adf758d8cff9f0b3a6d160f54419746791b99f8b&tochange=5db3b0cf00bf579b08aa2452b5aca1f05896fd54&selectedJob=167413782 Failure log: https://treeherder.mozilla.org/logviewer.html#?job_id=167413782&repo=autoland&lineNumber=8093 Backout link: https://hg.mozilla.org/integration/autoland/rev/5db3b0cf00bf579b08aa2452b5aca1f05896fd54

Ooof, that's a new one. Thanks, Investigating.

We're running too long because on Linux, the mouse floats over the first tab, warming it up. The TabSwitchDone event, which this test waits for a bunch, only fires after warmed tabs are evicted, which is after a few seconds by default. So I've modified this test to reduce the eviction time to 50 milliseconds. This allows the test to continue running with warming enabled, but not time out.

Pushed by mconley@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/664c633802d4 Enable tab warming by default for Nightly builds. r=dao

Backed out for frequently failing mochitest dom/html/test/test_fullscreen-api-race.html (bug 1445330): https://hg.mozilla.org/mozilla-central/rev/943930f3737f3b0850cc7e14c2fe23e4f5f5518b

I think I have a fix for the test failure. Baking on try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e99a6507815ba8b3cfbe7d2efc2f7db8a9854cf7

19 runs of mochitest-2 running the test are green with my fix - I'm fairly confident that cinches it. Patch coming up.

So the story here is that the DOM Fullscreen stuff tries to ensure that the DocShell is activated when going into fullscreen. If it's not activated, we throw an error here: https://searchfox.org/mozilla-central/rev/6e96a3f1e44e286ddae5fdafab737709741d237a/dom/base/nsDocument.cpp#11160 The test that was failing opens tabs from content using window.open, and the async tab switcher (with warming enabled) was only activating the DocShell _after_ entering STATE_LOADED. I think that's fine for warming tabs, but for tabs that aren't being warmed, I think we can safely fall back to activating the DocShell inside STATE_LOADING.

Bah, sorry dao, MozReview is making me ask for your review again. :/

Comment on attachment 8959600 [details] Bug 1423220 - Enable tab warming by default for Nightly builds. https://reviewboard.mozilla.org/r/228408/#review234266

Comment on attachment 8959599 [details] Bug 1423220 - Don't delay activating the DocShell for tabs that we're rendering by switching and not warming. https://reviewboard.mozilla.org/r/228406/#review234272 Chatted in IRC about maybe checking if this is the requestedTab, rather than checking the warming set. I think it would only matter for pathological tests, though, so r+ for whichever direction you choose.

(In reply to Doug Thayer [:dthayer] from comment #19) Yeah, I like the requestedTab approach better. Thanks! Try build looks good: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e689591dc95f0638e749c6ca38c8f16eb1555b45 Landing...

Pushed by mconley@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/8ff03a020b69 Don't delay activating the DocShell for tabs that we're rendering by switching and not warming. r=dthayer https://hg.mozilla.org/integration/autoland/rev/beae66d4b661 Enable tab warming by default for Nightly builds. r=dao

https://hg.mozilla.org/mozilla-central/rev/8ff03a020b69 https://hg.mozilla.org/mozilla-central/rev/beae66d4b661