Oilpan: make XHR progress event throttling finalization safe.

Oilpan: make XHR progress event throttling finalization safe.

Move the XHR event throttling object to the heap. It is a timer object,
hence it must be eagerly finalized so as to prevent unsafe accesses
should it instead be lazy sweepable.

Part objects cannot be eagerly finalized on their own, hence this is
accomplished by moving the object to the heap. For simplicity, we keep
it as a separate heap object non-Oilpan also.

R=haraken
BUG=491488
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197904

[sof, 2015-06-25 12:36:49]

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

[sof, 2015-06-25 12:36:49]

please take a look.

let's try this again. On balance, i think i prefer having this check over the
alternatives.

[haraken, 2015-06-25 23:31:17]

On 2015/06/25 12:36:49, sof wrote:
> please take a look.
> 
> let's try this again. On balance, i think i prefer having this check over the
> alternatives.

Can we make XMLHttpRequestProgressEventThrottle on-heap allocated and use
EAGER_SWEEP or pre-finalizer?

I'm not really happy about using Heap::willObjectBeLazilySwept in terms of
reducing the oilpan programming rule. In my ideal world, I want to have a simple
rule like "you can use a pre-finalizer to avoid destruction ordering issues.
Period." or something like that.

[sof, 2015-06-26 09:03:12]

On 2015/06/25 23:31:17, haraken wrote:
> On 2015/06/25 12:36:49, sof wrote:
> > please take a look.
> > 
> > let's try this again. On balance, i think i prefer having this check over
the
> > alternatives.
> 
> Can we make XMLHttpRequestProgressEventThrottle on-heap allocated and use
> EAGER_SWEEP or pre-finalizer?
> 
> I'm not really happy about using Heap::willObjectBeLazilySwept in terms of
> reducing the oilpan programming rule. In my ideal world, I want to have a
simple
> rule like "you can use a pre-finalizer to avoid destruction ordering issues.
> Period." or something like that.

ok, let's move it into the heap instead. 

(I think it is still a little too early to limit our options and choices when it
comes to eager finalization.)

[haraken, 2015-06-26 09:57:31]

LGTM

[sof, 2015-06-26 10:44:47]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-06-26 10:44:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1200413004/20001

[commit-bot: I haz the power, 2015-06-26 10:47:52]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197904