Removing references to webrtc::VideoSendStream::DegradationPreference.

It was replaced be webrtc::DegradationPreference in this CL:
https://webrtc-review.googlesource.com/c/src/+/77024

But some downstream code was still referencing it.

Bug: webrtc:8830
Change-Id: Ibd0a3d15df7f13473c0f37a2493dd70cec6c0482
Reviewed-on: https://webrtc-review.googlesource.com/78082
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23335}
diff --git a/api/rtpparameters.h b/api/rtpparameters.h
index ba02fd2..96df9ce 100644
--- a/api/rtpparameters.h
+++ b/api/rtpparameters.h
@@ -83,10 +83,6 @@
   MAINTAIN_RESOLUTION,
   // Try to strike a "pleasing" balance between frame rate or resolution.
   BALANCED,
-  // TODO(deadbeef): Remove once downstream code referencing
-  // "webrtc::VideoSendStream::DegradationPreference::kMaintainResolution" is
-  // updated.
-  kMaintainResolution = MAINTAIN_RESOLUTION
 };
 
 extern const double kDefaultBitratePriority;
diff --git a/call/video_send_stream.h b/call/video_send_stream.h
index 620719e..848902f 100644
--- a/call/video_send_stream.h
+++ b/call/video_send_stream.h
@@ -264,11 +264,6 @@
   // When a stream is stopped, it can't receive, process or deliver packets.
   virtual void Stop() = 0;
 
-  // TODO(deadbeef): Remove once downstream code referencing
-  // "webrtc::VideoSendStream::DegradationPreference::kMaintainResolution" is
-  // updated.
-  using DegradationPreference = webrtc::DegradationPreference;
-
   virtual void SetSource(
       rtc::VideoSourceInterface<webrtc::VideoFrame>* source,
       const DegradationPreference& degradation_preference) = 0;