Guard ResourceLoader::didReceiveData in error case.

Guard ResourceLoader::didReceiveData in error case.

A subresource can receive a body on a 404 if its call to
CachedResource::error() happens around a nested message loop. This can
cause a crash when data finally is received.

This is a regression brought about by refactoring, I thought I fixed
this in https://bugs.webkit.org/show_bug.cgi?id=103563 , but the fix
dissapeared.

Tested in a content_browsertest, see
https://codereview.chromium.org/15738007/ which can land after this is
gardened in.

BUG=241139
R=japhet

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=151609

[gavinp, 2013-05-30 15:39:57]

japhet,

WDYT?

[Nate Chapin, 2013-05-30 15:42:33]

Ah....nested message loops, that's why it's necessary. I mistook it for leftover
cruft. LGTM

Please add a comment so I don't delete it again.

[gavinp, 2013-05-30 18:00:28]

add comment

[gavinp, 2013-05-30 18:04:05]

Thanks for the review Nate.

I decline to say how much time I spent going through the blink refactorings to
determine why you removed this code.

Part of the problem is that the associated test for the original fix was
reverted in January and not updated; the new test should stick, so besides the
comment we will have continuous regression coverage.

[commit-bot: I haz the power, 2013-05-30 18:04:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-05-30 19:29:42]

Retried try job too often on linux_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_layo...

[commit-bot: I haz the power, 2013-05-30 19:41:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-05-30 20:29:41]

Retried try job too often on linux_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_layo...

[commit-bot: I haz the power, 2013-05-31 14:24:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-05-31 16:27:02]

Retried try job too often on win_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_layout...

[commit-bot: I haz the power, 2013-05-31 16:36:15]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-05-31 19:34:32]

Retried try job too often on win_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_layout...

[commit-bot: I haz the power, 2013-05-31 20:46:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-06-01 00:33:02]

Retried try job too often on win_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_layout...

[commit-bot: I haz the power, 2013-06-02 18:48:20]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/gavinp@chromium.org/15725010/4001

[commit-bot: I haz the power, 2013-06-02 21:13:32]

Change committed as 151609