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: Ia65be19b24c93db360a313f82a84bfae1a49bf2d Reviewed-on: https://webrtc-review.googlesource.com/23605 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Oskar Sundbom <ossu@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20929}