Changes places where we explicitly construct an Optional to instead use nullopt or the requisite value type only. This CL was uploaded by git cl split. Bug: None Change-Id: Ic83404f3b10ef7a9725ae1f4cf55e1b295cc9c5d Reviewed-on: https://webrtc-review.googlesource.com/23570 Commit-Queue: Oskar Sundbom <ossu@webrtc.org> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21571}