(Wangle) Implement collect* using mapSetCallback and shared_ptrs
Summary:
I figured it would make sense to implement all the collect* functions using a shared_ptr<Context>, instead of doing our manual reference counting and all that. Fulfilling the promise in the destructor seemed like the icing on the cake. Also saves some line of code.
Test Plan: Run all the tests.
Reviewed By: hans@fb.com
Subscribers: folly-diffs@, jsedgwick, yfeldblum, chalfant
FB internal diff:
D2015320
Signature: t1:
2015320:
1431106133:
ac3001b3696fc75230afe70908ed349102b02a45