292977 - Restoring window state can reenter state restoration

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Boris Zbarsky [:bzbarsky]]

Restoring window state fires a focus event on the last focused content, per bug
274784 comment 119.  This can trigger location changes or history navigation
which can reenter docshell code and state restoration.  I think docshell would
get very confused if this happens.

Comment 1

[Brian Ryner (not reading)]

Attachment: testcase

This triggers the behavior, I think (load the testcase, focus the textfield, go
back).	I could only get it to happen with a window focus listener; a focus
listener on the textbox doesn't seem to get fired (which is itself a bug if we
fire blur on it as you leave the page).  Nothing crashes or anything, but you
get:

WARNING: NS_ENSURE_TRUE(mRequest) failed, file
/builds/mozilla/bfcache/mozilla/netwerk/protocol/file/src/nsFileChannel.cpp,
line 172

if the testcase is local.  The worst I can visibly see happening is that the
page is nuked from the back cache, but there may be other side-effects.

Comment 2

[Brian Ryner (not reading)]

The focused content doesn't see a blur as the page is hidden nor does it see a
focus as the page is restored (the ESM sees it as already focused, I think). 
This is probably ok IMO.  So I think the only way to trigger this is via the
focus event on the window.

Comment 3

[Brian Ryner (not reading)]

targetting to beta for further investigation

Comment 4

[Brian Ryner (not reading)]

With all of the window state restoration happening async now, I don't think this
is an issue any longer.  I no longer see the aforementioned assert or any other
problems with this test case (testing with the patch for bug 303267 applied so
that event handlers are correctly restored.