Instead, use a neat trick with union to ensure that we have a T only
when we're supposed to (and just a bunch of unused memory otherwise).
This is how std::optional behaves, so it makes sense for us to do the
same (and it's convenient, too, since we don't have to pay for the
default-constructed T, and we support types that don't have default
constructors).
Doing this became possible recently when we dropped support for MSVC
2013, which didn't support unions containing non-trivial types.
Review-Url: https://codereview.webrtc.org/1896833004
Cr-Commit-Position: refs/heads/master@{#12664}
This propagated into various other places. Also had to #include headers that
were implicitly pulled by "scoped_ptr.h".
BUG=webrtc:5520
Review URL: https://codereview.webrtc.org/1920043002
Cr-Commit-Position: refs/heads/master@{#12501}
No operator== that accepts one unique_ptr<T> and one T*. No implicit
conversion to bool. No rtc_make_scoped_ptr function.
BUG=webrtc:5520
Review URL: https://codereview.webrtc.org/1803833002
Cr-Commit-Position: refs/heads/master@{#12048}
