The following tests were disabled in browser/components/newtab/test/browser/browser.ini due to new Fission platform triage:
browser_aboutwelcome_multistage.js

Full diff:

--- a/browser/components/newtab/test/browser/browser.ini
+++ b/browser/components/newtab/test/browser/browser.ini
@@ -15,16 +17,18 @@ prefs =
   browser.newtabpage.activity-stream.feeds.system.topstories=true
   browser.newtabpage.activity-stream.feeds.section.topstories=true
   browser.newtabpage.activity-stream.feeds.section.topstories.options={"provider_name":""}
   messaging-system.log=all
 
 [browser_aboutwelcome_focus.js]
 [browser_aboutwelcome_simplified.js]
 [browser_aboutwelcome_multistage.js]
+skip-if =
+  fission && os == "linux" && asan # New platform triage
 [browser_aboutwelcome_rtamo.js]
 skip-if = (os == "linux") # Test setup only implemented for OSX and Windows
 [browser_aboutwelcome_attribution.js]
 skip-if = (os == "linux") # Test setup only implemented for OSX and Windows
 [browser_aboutwelcome_observer.js]
 [browser_as_load_location.js]
 [browser_as_render.js]
 [browser_asrouter_snippets.js]

See the following try push for failures:
https://treeherder.mozilla.org/jobs?repo=try&revision=ad7a18fdad3b8e35b44152c16d94babb80387cd8

To run these failures in your own try push, first revert the skip-if
annotations, then run:

$ ./mach try fuzzy --rebuild 3 browser/components/newtab/test/browser/browser.ini

Then use the fuzzy interface to select the task(s) which are relevant to the
removed skip-if expression(s). Please note the failure may be intermittent
and/or been fixed since the triage took place.

We need to determine whether this browser-chrome test failure should block shipping Fission. Tracking for Fission Milestone M7a for the initial audit. Then we can decide whether to move this bug to Fission M8 or post-MVP (Fission Future).

Here is a recent Try run for Fission browser-chrome:

https://treeherder.mozilla.org/jobs?repo=try&revision=ad7a18fdad3b8e35b44152c16d94babb80387cd8

I don't see any browser_aboutwelcome_multistage.js failures in recent Fission browser-chrome try runs (before this new skip-if = fission && os == "linux" && asan annotation was added). This annotation might be a false positive. We've had some other false positive bug reports for Fission browser-chrome failures. can try removing the new annotation and seeing what happens.

https://searchfox.org/mozilla-central/rev/bf8d5de8528036c09590009720bc172882845b80/browser/components/newtab/test/browser/browser.ini#22-24

[browser_aboutwelcome_multistage.js]
skip-if =
  fission && os == "linux" && asan # Bug 1713896 - new Fission platform triage

(In reply to Chris Peterson [:cpeterson] from comment #2)

I don't see any browser_aboutwelcome_multistage.js failures in recent Fission browser-chrome try runs (before this new skip-if = fission && os == "linux" && asan annotation was added). This annotation might be a false positive. We've had some other false positive bug reports for Fission browser-chrome failures. can try removing the new annotation and seeing what happens.

https://searchfox.org/mozilla-central/rev/bf8d5de8528036c09590009720bc172882845b80/browser/components/newtab/test/browser/browser.ini#22-24

[browser_aboutwelcome_multistage.js]
skip-if =
  fission && os == "linux" && asan # Bug 1713896 - new Fission platform triage

+1, looks like a false alarm and should be safe to remove skip test condition

Kashav, from comment 3, this looks like another false positive that can be re-enabled, if you can.

https://hg.mozilla.org/mozilla-central/rev/7cfe9023caa7