This replaces references to the ResourceAdaptationProcessor with references to its interface. This would make it possible to have alternative implementations or inject fake/mock implementations for testing. The VideoStreamAdapter is still responsible for constructing the ResourceAdaptationProcessor, but beyond construction it is agnostic towards the implementation. With this CL, I claim https://crbug.com/webrtc/11222 complete. TBR=ilnik@webrtc.org Bug: webrtc:11222 Change-Id: I6e7a73bf1d0b5e97bc694f66180a747b27ffb018 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174160 Reviewed-by: Henrik Boström <hbos@webrtc.org> Reviewed-by: Evan Shrubsole <eshr@google.com> Commit-Queue: Henrik Boström <hbos@webrtc.org> Cr-Commit-Position: refs/heads/master@{#31148}