Oilpan: Fix a cycle caused by SVGPropertyTearOffBase::m_contextElement

Oilpan: Fix a cycle caused by SVGPropertyTearOffBase::m_contextElement

For the reason described in the bug, using a Member for SVGPropertyTearOffBase::m_contextElement
causes a cycle. To break the cycle, this CL changes it to a raw pointer.
The raw pointer is safe because the context element is guaranteed to be kept alive
by a V8 wrapper of the SVG tear off object.

BUG=528275
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201796

[haraken, 2015-09-04 12:45:21]

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

[haraken, 2015-09-04 12:45:21]

PTAL

[sof, 2015-09-04 12:56:15]

thanks for quick turnaround, lgtm.

[haraken, 2015-09-04 12:58:18]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2015-09-04 12:58:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1330673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1330673002/1

[haraken, 2015-09-04 12:58:44]

We still have the following m_contextElements.

core/html/parser/HTMLTreeBuilder.h:        RefPtrWillBeMember<HTMLStackItem>
m_contextElementStackItem;
core/svg/SVGPathSeg.h:    RawPtrWillBeMember<SVGElement> m_contextElement;
core/svg/SVGPathSegList.h:    RawPtrWillBeMember<SVGPathElement>
m_contextElement;
core/svg/SVGViewSpec.h:    RawPtrWillBeMember<SVGSVGElement> m_contextElement;
core/svg/SVGAnimatedTypeAnimator.h:    RawPtrWillBeMember<SVGElement>
m_contextElement;

I guess those would be no problem but am checking.

[commit-bot: I haz the power, 2015-09-04 13:42:21]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201796

[sof, 2015-09-08 09:52:24]

On 2015/09/04 12:58:44, haraken wrote:
> We still have the following m_contextElements.
> 
> core/html/parser/HTMLTreeBuilder.h:        RefPtrWillBeMember<HTMLStackItem>
> m_contextElementStackItem;
> core/svg/SVGPathSeg.h:    RawPtrWillBeMember<SVGElement> m_contextElement;
> core/svg/SVGPathSegList.h:    RawPtrWillBeMember<SVGPathElement>
> m_contextElement;
> core/svg/SVGViewSpec.h:    RawPtrWillBeMember<SVGSVGElement> m_contextElement;
> core/svg/SVGAnimatedTypeAnimator.h:    RawPtrWillBeMember<SVGElement>
> m_contextElement;
> 
> I guess those would be no problem but am checking.

animations/svg-attribute-interpolation/svg-d-interpolation.html is running into
a leak, but I can't see how/where it enters.

 (
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan%...
)

[haraken, 2015-09-08 11:41:00]

On 2015/09/08 09:52:24, sof wrote:
> On 2015/09/04 12:58:44, haraken wrote:
> > We still have the following m_contextElements.
> > 
> > core/html/parser/HTMLTreeBuilder.h:        RefPtrWillBeMember<HTMLStackItem>
> > m_contextElementStackItem;
> > core/svg/SVGPathSeg.h:    RawPtrWillBeMember<SVGElement> m_contextElement;
> > core/svg/SVGPathSegList.h:    RawPtrWillBeMember<SVGPathElement>
> > m_contextElement;
> > core/svg/SVGViewSpec.h:    RawPtrWillBeMember<SVGSVGElement>
m_contextElement;
> > core/svg/SVGAnimatedTypeAnimator.h:    RawPtrWillBeMember<SVGElement>
> > m_contextElement;
> > 
> > I guess those would be no problem but am checking.
> 
> animations/svg-attribute-interpolation/svg-d-interpolation.html is running
into
> a leak, but I can't see how/where it enters.
> 
>  (
>
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan%...
> )

Thanks, let me take a look tomorrow.

[sof, 2015-09-08 12:50:29]

On 2015/09/08 11:41:00, haraken wrote:
> On 2015/09/08 09:52:24, sof wrote:
> > On 2015/09/04 12:58:44, haraken wrote:
> > > We still have the following m_contextElements.
> > > 
> > > core/html/parser/HTMLTreeBuilder.h:       
RefPtrWillBeMember<HTMLStackItem>
> > > m_contextElementStackItem;
> > > core/svg/SVGPathSeg.h:    RawPtrWillBeMember<SVGElement> m_contextElement;
> > > core/svg/SVGPathSegList.h:    RawPtrWillBeMember<SVGPathElement>
> > > m_contextElement;
> > > core/svg/SVGViewSpec.h:    RawPtrWillBeMember<SVGSVGElement>
> m_contextElement;
> > > core/svg/SVGAnimatedTypeAnimator.h:    RawPtrWillBeMember<SVGElement>
> > > m_contextElement;
> > > 
> > > I guess those would be no problem but am checking.
> > 
> > animations/svg-attribute-interpolation/svg-d-interpolation.html is running
> into
> > a leak, but I can't see how/where it enters.
> > 
> >  (
> >
>
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan%...
> > )
> 
> Thanks, let me take a look tomorrow.

https://codereview.chromium.org/1328223002/ takes care of it for me, weakening
some more back/up references for SVGPathSegLists. But, hmm, this is a bit
unsatisfactory.