[WIP]Oilpan: checking for nearly-dead observers.

[WIP]Oilpan: checking for nearly-dead observers.

[haraken, 2015-05-09 14:50:32]

haraken@chromium.org changed reviewers:
+ haraken@chromium.org

[haraken, 2015-05-09 14:50:33]

Thanks for the CL.

IMHO, I think it would be OK to add this complexity because:

- The added code is a temporary one -- it will be removed when shipping Oilpan
for the Node hierarchy.

- I cannot come up with any other idea to enable lazy sweeping (which is needed
to achieve acceptable performance for core/animations/, html/canvas/ etc). If we
don't enable lazy sweeping, we cannot enable oilpan for core/animations/,
html/canvas/ etc until we enable oilpan for the Node hierarchy. This means that
we have to enable oilpan for a ton of things in one go, which sounds risky.

Overall, I think it would be reasonable to land this CL, enable lazy sweeping,
and enable oilpan for core/animations/, html/canvas/ etc more incrementally.

https://codereview.chromium.org/1132053002/diff/1/Source/core/dom/ContextLife...
File Source/core/dom/ContextLifecycleNotifier.cpp (right):

https://codereview.chromium.org/1132053002/diff/1/Source/core/dom/ContextLife...
Source/core/dom/ContextLifecycleNotifier.cpp:46: // FIXME: Oilpan: At the
moment, it's possible that a ActiveDOMObject

Not related to this CL, I think this FIXME is valid only in non-oilpan. In
oilpan, the observers are guaranteed to be kept alive during the iteration.