Remove function for converting uri into ExtensionType This removes one of the lists of all supported extensions Bug: webrtc:7472 Change-Id: I0c27239d91ef14ca4a3aa0c00588fa2b9cf10e0c Reviewed-on: https://webrtc-review.googlesource.com/100523 Reviewed-by: Niels Moller <nisse@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#24752}