PSA: optional.h moved from rtc_base/ to api/

[Karl Wiberg]

As of this CL (landed yesterday), optional now lives in webrtc/api/ instead of webrtc/rtc_base/. In about two weeks, I plan to land a CL that removes the backwards compatibility header in the old location. Anyone #including optional.h directly needs to start using the new path before then.

--

Karl Wiberg |

Software Engineer |

kwi...@google.com |

+46 70 696 1024