This enables callers to specify a way to determine the correct window to
dispatch the PluginCrashed event to should the GMP actor crash.
We need a way to determine the correct window at crash time, as the GMP's
window can change at runtime. For example, if the GMP is being used for
unencrypted decoding, the <video> element can be moved to a new browser window
at runtime.
Note: I don't handle disconnecting the GMPCrashHandlers in this patch; we do
delete the GMPCrashHandlers in this patch when their associated GMP crashes, and
in the next patch we handle disconnecting GMPCrashHandlers in the case where
we don't crash.
MozReview-Commit-ID: DrwcZAB6Ys0
--HG--
extra : rebase_source : 8da188b68456914773e6adae8cbccd6bf6a6e7a7
e0a9078a6f