Have ProcessingInstruction's XSLT event listener keep a weak backreference

Have ProcessingInstruction's XSLT event listener keep a weak backreference

To avoid an unnecessary strong-reference cycle between
ProcessingInstruction and its owned "XSLT event listener", have the
latter keep an effectively-weak reference. ProcessingInstruction is
responsible to detach itself and clear that weak reference when it
is finalized.

R=haraken
BUG=367689
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185858

[sof, 2014-11-23 17:58:03]

sigbjornf@opera.com changed reviewers:
+ haraken@chromium.org, oilpan-reviews@chromium.org, tasak@chromium.org

[sof, 2014-11-23 17:58:03]

Please take a look.

The Persistent<> back reference from this EventListener makes most XSL(T) tests
leak documents with Oilpan enabled:


https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Oil...

There really is no reason why that reference needs to be strong, so tried to
express that. A bit quirkily done but I can't think of a simpler way (it would
be nice to have EventListeners on the heap also though.)

[haraken, 2014-11-24 01:17:01]

Thanks for the fix, LGTM.

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
File Source/core/dom/ProcessingInstruction.cpp (right):

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
Source/core/dom/ProcessingInstruction.cpp:70: if (m_listenerForXSLT)

We can call clearEventListenerForXSLT().

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
File Source/core/dom/ProcessingInstruction.h (right):

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
Source/core/dom/ProcessingInstruction.h:58: class PIEventListener {

PIEventListener => ProcessingInstructionEventListener

[sof, 2014-11-24 06:15:39]

Many thanks for the quick review.

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
File Source/core/dom/ProcessingInstruction.cpp (right):

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
Source/core/dom/ProcessingInstruction.cpp:70: if (m_listenerForXSLT)
On 2014/11/24 01:17:00, haraken wrote:
> 
> We can call clearEventListenerForXSLT().

Yes, done.

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
File Source/core/dom/ProcessingInstruction.h (right):

https://codereview.chromium.org/738443003/diff/1/Source/core/dom/ProcessingIn...
Source/core/dom/ProcessingInstruction.h:58: class PIEventListener {
On 2014/11/24 01:17:00, haraken wrote:
> 
> PIEventListener => ProcessingInstructionEventListener

Renamed.

[sof, 2014-11-24 06:15:46]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2014-11-24 06:16:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/738443003/20001

[commit-bot: I haz the power, 2014-11-24 07:28:07]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=185858