1327380 - [e10s] Browser suddently disables e10s forever and never tells how to enable it again

Status: RESOLVED WONTFIX

(Core :: Disability Access APIs, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
STR_1:
1. Launch Firefox
2. Press Win+"=" to use Windows Magnifier. Use any other accessibility tool if you use less popular OS
3. Switch to another application, then back to Firefox
4. Close Firefox. Close Windows Magnifier
5. Launch Firefox
6. Close Firefox. Launch Firefox

AR:
 Step 3 - Firefox says "Accessibility support is partially disabled due to compatibility issues
          with new Nightly features."
 Step 5 - e10s is disabled forever, but browser doesn't tell that user should expect broken behavior

ER:  At least one of the following
 X) Tell me that the thing is broken
     In Step 5, browser should warn user that he should expect browser to be more broken than earlier.
     I did NOT expected it to be broken, and opened many important tabs in private mode (in order
     not to spam History). SURPRISINGLY, Firefox hung and lost all the tabs.
     All work was lost.
     Users develop specific behavior when they use browser, i.e. they know what to expect from their
     actions and what they shouldn't do while using the browser, e.g. open many heavy tabs in non-e10s
     Messing with user's expectations by creating hidden breakages clearly indicates a bad software.
 Y) Enable e10s after the next restart
     Ok, let browser silently break in Step 5 if it wants it so badly, but fix it in Step 6
 Z) Tell me how I can enable e10s
     Browser shouldn't HIDE information from user. There's clearly a way to enable e10s again.
     At the very least, browser should tell, for _how_long_ it wants user to suffer from non-e10s.


This was regressed 2 times:
 [1] Bug 1241959 (between 2016-01-23 and 2016-01-24) - browser no longer tells the workaround  (see Z)
 [2] Bug 1260190 (between 2016-04-05 and 2016-04-06) - browser started to disable e10s forever (see Y)

Regression ranges:
> [1] https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=3752abafdf19b08a543ce4ce243b2bb7c74b664d&tochange=e7cfbfa5847cdfbdc0f103cb4c3c36238c0e976c
> [2] https://hg.mozilla.org/integration/fx-team/pushloghtml?fromchange=8649e83a43b9c1fc271d43e50ade50966c7e94b9&tochange=1733bd822f0f9bf24a70b6fc3f61521a81a216fd

Comment 1

[David Bolter [:davidb] (NeedInfo me for attention)]

I don't think we'll fix this before it becomes overshadowed by us working in e10s mode.