1425092 - Add MozPromise::Await method

Status: NEW

(Core :: XPCOM, enhancement)

Description

[Jean-Yves Avenard [:jya]]

In bug 1404997, we added an Await method that takes a MozPromise and wait synchronously until it's completed, and when so will run in the current thread a resolve or reject method.

Moving it to MozPromise allows for better move sematics and can be made to use ResolveOrRejectValue instead.

We would have:
ResolveOrRejectValue MozPromise::Await();

ResolveOrRejectValue::Then(Function&& aResolve, Function&& aReject).

Which would allow things like:

RefPtr<MozPromise> p = AsyncMethod();
p->Await()->Then(Function&& Resolve, Function&& Reject);