The following tests were disabled in browser/components/sessionstore/test/browser.ini due to new Fission platform triage:
browser_async_flushes.js
browser_ignore_updates_crashed_tabs.js
browser_sessionHistory.js
browser_async_window_flushing.js
browser_crashedTabs.js
browser_revive_crashed_bg_tabs.js
browser_615394-SSWindowState_events_undoCloseWindow.js
browser_async_duplicate_tab.js
browser_formdata.js
browser_tabicon_after_bg_tab_crash.js
browser_unrestored_crashedTabs.js

Full diff:

diff --git a/browser/components/sessionstore/test/browser.ini b/browser/components/sessionstore/test/browser.ini
--- a/browser/components/sessionstore/test/browser.ini
+++ b/browser/components/sessionstore/test/browser.ini
@@ -72,51 +88,63 @@ prefs =
 #disabled-for-intermittent-failures--bug-766044, browser_459906_empty.html
 #disabled-for-intermittent-failures--bug-766044, browser_459906_sample.html
 #disabled-for-intermittent-failures--bug-765389, browser_461743_sample.html
 
 [browser_aboutPrivateBrowsing.js]
 [browser_aboutSessionRestore.js]
 skip-if = (verify && debug && (os == 'win' || os == 'mac'))
 [browser_async_duplicate_tab.js]
+skip-if =
+  fission && os == "mac" && !debug  # New platform triage
 support-files = file_async_duplicate_tab.html
 [browser_async_flushes.js]
 support-files = file_async_flushes.html
 run-if = e10s && crashreporter
-skip-if = debug # bug 1167933
+skip-if =
+  debug # bug 1167933
   apple_silicon  # crash
+  fission && (os != "linux" || asan)  # New platform triage
 [browser_async_remove_tab.js]
 run-if = e10s
 skip-if =
   debug # bug 1211084
   os == 'linux' && bits == 64 && !debug # Bug 1677540
 [browser_attributes.js]
 [browser_backup_recovery.js]
 skip-if = (verify && debug && (os == 'linux'))
 [browser_broadcast.js]
 [browser_capabilities.js]
 [browser_cleaner.js]
 [browser_crashedTabs.js]
-skip-if = !e10s || !crashreporter || verify
+skip-if =
+  !e10s || !crashreporter || verify
   apple_silicon  # crash
+  fission && os == "win" && !debug  # New platform triage
 [browser_multiple_select_after_load.js]
 [browser_pinned_tabs.js]
 skip-if = debug || ccov # Bug 1625525
   apple_silicon  # crash
 [browser_unrestored_crashedTabs.js]
-skip-if = !e10s || !crashreporter
+skip-if =
+  !e10s || !crashreporter
   apple_silicon  # crash
+  fission && os == "win" && !debug  # New platform triage
 [browser_revive_crashed_bg_tabs.js]
-skip-if = !e10s || !crashreporter
+skip-if =
+  !e10s || !crashreporter
   apple_silicon  # crash
+  fission && os == "win" && !debug  # New platform triage
 [browser_dying_cache.js]
 skip-if = (os == 'win') # bug 1331853
 [browser_dynamic_frames.js]
 [browser_formdata.js]
-skip-if = verify && debug
+skip-if =
+    verify && debug
+    fission && ((os == "linux"  && asan) || os == "mac")  # New platform triage
 [browser_formdata_cc.js]
 [browser_formdata_format.js]
 skip-if = !debug && (os == 'linux') # Bug 1535645
 [browser_formdata_password.js]
 support-files = file_formdata_password.html
 [browser_formdata_xpath.js]
 [browser_frametree.js]
 [browser_frame_history.js]
@@ -136,17 +164,19 @@ skip-if = e10s # Bug 1271024
 skip-if = true # Bug 1646894
 [browser_restore_redirect.js]
 [browser_restoreTabContainer.js]
 [browser_restore_cookies_noOriginAttributes.js]
 [browser_scrollPositions.js]
 skip-if = !fission
 [browser_scrollPositionsReaderMode.js]
 [browser_sessionHistory.js]
-skip-if = tsan # Bug 1651907, highly frequent on TSan
+skip-if =
+  tsan # Bug 1651907, highly frequent on TSan
+  fission && os == "win" && !debug  # New platform triage
 support-files =
   file_sessionHistory_hashchange.html
 [browser_sessionStorage.js]
 skip-if = fission # Bug 1700623
 [browser_sessionStorage_size.js]
 [browser_sizemodeBeforeMinimized.js]
 [browser_tab_label_during_restore.js]
 [browser_swapDocShells.js]
@@ -228,17 +258,20 @@ skip-if = true # Needs to be rewritten a
 [browser_607016.js]
 [browser_615394-SSWindowState_events_duplicateTab.js]
 [browser_615394-SSWindowState_events_setBrowserState.js]
 skip-if = verify && debug && os == 'mac'
 [browser_615394-SSWindowState_events_setTabState.js]
 [browser_615394-SSWindowState_events_setWindowState.js]
 [browser_615394-SSWindowState_events_undoCloseTab.js]
 [browser_615394-SSWindowState_events_undoCloseWindow.js]
-skip-if = (os == 'win' && !debug) || (os == 'linux') #Bug 1572554
+skip-if =
+    os == 'win' && !debug  # Bug 1572554
+    os == 'linux'  # Bug 1572554
+    fission && os == 'mac' && !debug  # New platform triage
 [browser_618151.js]
 [browser_623779.js]
 [browser_624727.js]
 [browser_628270.js]
 [browser_635418.js]
 [browser_636279.js]
 [browser_637020.js]
 [browser_645428.js]
@@ -272,16 +305,18 @@ skip-if = true
 skip-if = os == "mac" || (os == "linux" && debug) || (os == "linux" && bits == 64) || (os == "linux" && asan && bits == 64) || (os == 'win' && debug) # linux, Bug 1348583 # Bug 1430977
 
 [browser_906076_lazy_tabs.js]
 skip-if = os == "linux" && bits == 64 && os_version == "18.04" # bug 1446464
 [browser_911547.js]
 [browser_1284886_suspend_tab.js]
 skip-if = !e10s
 [browser_async_window_flushing.js]
+skip-if =
+  fission && (os != "linux" || asan)  # New platform triage
 [browser_focus_after_restore.js]
 [browser_forget_async_closings.js]
 [browser_movePendingTabToNewWindow.js]
 [browser_multiple_navigateAndRestore.js]
 skip-if = debug && os == 'linux' && bits == 64 #Bug 1570468
 run-if = e10s
 [browser_newtab_userTypedValue.js]
 skip-if = verify && debug
@@ -303,18 +338,20 @@ skip-if =
 [browser_undoCloseById.js]
 skip-if = debug
 [browser_docshell_uuid_consistency.js]
 
 [browser_closed_objects_changed_notifications_tabs.js]
 [browser_closed_objects_changed_notifications_windows.js]
 [browser_duplicate_history.js]
 [browser_tabicon_after_bg_tab_crash.js]
-skip-if = !crashreporter || !e10s # Tabs can't crash without e10s
+skip-if =
+  !crashreporter || !e10s # Tabs can't crash without e10s
   apple_silicon  # crash
+  fission && os == "win" && !debug  # New platform triage
 [browser_tabs_in_urlbar.js]
 
 [browser_cookies.js]
 [browser_cookies_legacy.js]
 [browser_cookies_privacy.js]
 [browser_speculative_connect.js]
 [browser_1446343-windowsize.js]
 skip-if = os == 'linux' # Bug 1600180
@@ -326,9 +363,10 @@ skip-if = true #Bug 1455602
 [browser_restore_container_tabs_oa.js]
 [browser_restore_private_tab_os.js]
 [browser_reopen_all_windows.js]
 [browser_ignore_updates_crashed_tabs.js]
 run-if = e10s && crashreporter
 skip-if = 
   asan
   apple_silicon # crash
-  (os == "win" && fission && verify) # bug 1709907
\ No newline at end of file
+  (os == "win" && fission && verify) # bug 1709907
+  fission && os == "win" && !debug  # New platform triage

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/sessionstore/test/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

Looks like many of the mac/win failures are opt-only. Probably related to event timing.

The browser_async_window_flushing.js failures might be bug 1701337, and browser_async_flushes.js failures might be bug 1536528, but now generalized to other platforms.

The browser_ignore_updates_crashed_tabs.js looks like it's probably bug 1709907.

I don't see cases of the other issues right now in the linked try run (filtered: https://treeherder.mozilla.org/jobs?repo=try&revision=ad7a18fdad3b8e35b44152c16d94babb80387cd8&test_paths=browser%2Fcomponents%2Fsessionstore%2Ftest%2Fbrowser.ini), so they appear to be quite intermittent.

(In reply to Nika Layzell [:nika] (ni? for response) from comment #3)

The browser_async_window_flushing.js failures might be bug 1701337, and browser_async_flushes.js failures might be bug 1536528, but now generalized to other platforms.

Neither bug 1701337 nor bug 1536528 are Fission-specific, so we might be able to remove the new Fission annotations from browser_async_window_flushing.js and browser_async_flushes.js and see what happens.

I don't see cases of the other issues right now in the linked try run (filtered: https://treeherder.mozilla.org/jobs?repo=try&revision=ad7a18fdad3b8e35b44152c16d94babb80387cd8&test_paths=browser%2Fcomponents%2Fsessionstore%2Ftest%2Fbrowser.ini), so they appear to be quite intermittent.

Here are two browser_sessionHistory.js failures from recent Fission browser-chrome try runs (before these Fission skip-if annotations were added). There a few existing bugs for failures with this test.

https://treeherder.mozilla.org/push-health/push?repo=try&revision=ad7a18fdad3b8e35b44152c16d94babb80387cd8&testGroup=ki&selectedTest=browsercomponentssessionstoretestbrowsersessionHistoryjs&selectedTaskId=

https://treeherder.mozilla.org/push-health/push?repo=try&revision=68a497fb35adce3f9f48888d7b7a7fd5cc795056&testGroup=ki&selectedTest=browsercomponentssessionstoretestbrowsersessionHistoryjs&selectedTaskId=

Here is a browser_async_duplicate_tab.js failure, which might be a duplicate of bug 1701836:

https://treeherder.mozilla.org/push-health/push?repo=try&revision=68a497fb35adce3f9f48888d7b7a7fd5cc795056&testGroup=ki&selectedTest=browsercomponentssessionstoretestbrowserasyncduplicatetabjs&selectedTaskId=&selectedJobName=browser%2Fcomponents%2Fsessionstore%2Ftest%2Fbrowser_sessionHistory.js+test-windows10-64-qr%2Fdebug-mochitest-browser-chrome-fis-e10s-5

Kashav, bug 1715264 fixed the following sessionstore tests listed in comment 0:

browser_async_flushes.js
browser_sessionHistory.js

But the following sessionstore tests still have skip-if = fission annotations to be fixed (or accepted) for Fission:

browser_async_duplicate_tab.js
browser_crashedTabs.js
browser_unrestored_crashedTabs.js
browser_revive_crashed_bg_tabs.js
browser_formdata.js
browser_sessionStorage.js (skipped in bug 1700623)
browser_615394-SSWindowState_events_undoCloseWindow.js
browser_async_window_flushing.js
browser_tabicon_after_bg_tab_crash.js
browser_ignore_updates_crashed_tabs.js

Nika triaged some of these test failures above in comment 3.

I'm tentatively assigning this sessionstore bug to you. If you think this bug should be split up into separate test bugs or reassigned to someone else, just let me know!

A try push with all "New platform triage" annotations removed shows:

• browser_async_window_flushing.js is failing quite consistently (I have patches to fix this in bug 1701337).
• browser_label_and_icon.js failed twice on OS X opt (bug 1638958).
• browser_sessionHistory.js timed out twice on Windows opt (bug 1646356).
• browser_formdata.js failed a few times on Linux opt and asan (bug 1703692).

No other test failed in 20 runs. I'll do another 20 runs, but it should be fine to remove the annotations and treat the failures as regular intermittents.

Most of these fail very rarely (if at all), and the ones that do already have
intermittent bugs filed.

See comment #6.

https://hg.mozilla.org/mozilla-central/rev/d7a7cf31026f