RtpSenderInterface::SetEncoderSelector

This cl/ adds a way of setting an EncoderSelector on a specific
RtpSenderInterface. This makes it possible to easily use different
EncoderSelector on different streams within the same or different PeerConnections.

The cl/ is almost identical to the impl. of RtpSenderInterface::SetFrameEncryptor.

Iff a EncoderSelector is set on the RtpSender, it will take precedence
over the VideoEncoderFactory::GetEncoderSelector.

Bug: webrtc:14122
Change-Id: Ief4f7c06df7f1ef4ce3245de304a48e9de0ad587
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/264542
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37150}

api/rtp_sender_interface.h

diff --git a/api/rtp_sender_interface.h b/api/rtp_sender_interface.h
index 9ffad68..48ea864 100644
--- a/api/rtp_sender_interface.h
+++ b/api/rtp_sender_interface.h
@@ -14,6 +14,7 @@
 #ifndef API_RTP_SENDER_INTERFACE_H_
 #define API_RTP_SENDER_INTERFACE_H_
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -26,6 +27,7 @@
 #include "api/rtc_error.h"
 #include "api/rtp_parameters.h"
 #include "api/scoped_refptr.h"
+#include "api/video_codecs/video_encoder_factory.h"
 #include "rtc_base/ref_count.h"
 #include "rtc_base/system/rtc_export.h"
 
@@ -96,6 +98,12 @@
   virtual void SetEncoderToPacketizerFrameTransformer(
       rtc::scoped_refptr<FrameTransformerInterface> frame_transformer);
 
+  // Sets a user defined encoder selector.
+  // Overrides selector that is (optionally) provided by VideoEncoderFactory.
+  virtual void SetEncoderSelector(
+      std::unique_ptr<VideoEncoderFactory::EncoderSelectorInterface>
+          encoder_selector) {}
+
  protected:
   ~RtpSenderInterface() override = default;
 };