Make Carbon plugin idle event source robust against changes during iteration

Make Carbon plugin idle event source robust against changes during iteration

Ensure that removing any plugin from the idle event source during iteration is safe (not just the currently-firing plugin). Also bullet-proofs against the possibility of nested iteration.

Refactors the idle event source to use a helper class, to reduce duplicate code.

BUG=33467
TEST=Scroll rapidly on a page with multiple instances of a Cabon plugin.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=38216

[pink (ping after 24hrs), 2010-02-05 17:31:32]

http://codereview.chromium.org/575023/diff/1/2
File webkit/glue/plugins/webplugin_delegate_impl_mac.mm (right):

http://codereview.chromium.org/575023/diff/1/2#newcode131
webkit/glue/plugins/webplugin_delegate_impl_mac.mm:131: // if that happens and
it's next on the list, increment the iterator
doesn't any change to the list while an iterator is in progress make the
iterator invalid and undefined, not just "if it's the next one"? What's the
documented behavior for stl? I fear this might just happen to work but isn't
guaranteed to.

[pink (ping after 24hrs), 2010-02-05 17:35:25]

stuart assures me this is ok for sets. LGTM.