James Teh 132a49a8a1 Bug 1626802 part 1: mscom: Provide a way for Interceptors to avoid unnecessary cross-thread QueryInterface calls. r=aklotz
When marshaling a11y calls from the content process, there are quite a lot of cross-thread QueryInterface calls (ipc::mscom::Interceptor::QueryInterfaceTarget).
Some of these are for special COM interfaces like IAgileObject and IFastRundown, which we could just special case in Interceptor::QueryInterface like we do for INoMarshal.
However, it seems there are a lot of other interfaces being queried and it's not clear why.
This patch adds a new HandlerProvider method: IsInterfaceMaybeSupported.
This allows implementations to indicate when there are interfaces which they definitely don't support, allowing the call to be answered without a cross-thread call.

Differential Revision: https://phabricator.services.mozilla.com/D69285

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extra : moz-landing-system : lando
2020-04-01 23:30:21 +00:00
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