Revert "Move rtp-specific config out of EncoderSettings."

This reverts commit bc900cb1d1810fcf678fe41cf1e3966daa39c88c.

Reason for revert: Broke downstream projects.

Original change's description:
> Move rtp-specific config out of EncoderSettings.
> 
> In VideoSendStream::Config, move payload_name and payload_type from
> EncoderSettings to Rtp.
> 
> EncoderSettings now contains configuration for VideoStreamEncoder only,
> and should perhaps be renamed in a follow up cl. It's no longer
> passed as an argument to VideoCodecInitializer::SetupCodec.
> 
> The latter then needs a different way to know the codec type,
> which is provided by a new codec_type member in VideoEncoderConfig.
> 
> Bug: webrtc:8830
> Change-Id: Ifcc691aef1ee6a95e43c0452c5e630d92a511cd6
> Reviewed-on: https://webrtc-review.googlesource.com/62062
> Commit-Queue: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
> Reviewed-by: Stefan Holmer <stefan@webrtc.org>
> Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22532}

TBR=brandtr@webrtc.org,magjed@webrtc.org,nisse@webrtc.org,stefan@webrtc.org

Change-Id: I01f06c1fcf21eb2cd40dca7d4f268614200ee490
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8830
Reviewed-on: https://webrtc-review.googlesource.com/63720
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22537}
diff --git a/modules/video_coding/video_codec_initializer.cc b/modules/video_coding/video_codec_initializer.cc
index 892113b..e473a16 100644
--- a/modules/video_coding/video_codec_initializer.cc
+++ b/modules/video_coding/video_codec_initializer.cc
@@ -26,15 +26,18 @@
 
 bool VideoCodecInitializer::SetupCodec(
     const VideoEncoderConfig& config,
+    const VideoSendStream::Config::EncoderSettings settings,
     const std::vector<VideoStream>& streams,
     bool nack_enabled,
     VideoCodec* codec,
     std::unique_ptr<VideoBitrateAllocator>* bitrate_allocator) {
-  if (config.codec_type == kVideoCodecMultiplex) {
-    VideoEncoderConfig associated_config = config.Copy();
-    associated_config.codec_type = kVideoCodecVP9;
-    if (!SetupCodec(associated_config, streams, nack_enabled, codec,
-                    bitrate_allocator)) {
+  if (PayloadStringToCodecType(settings.payload_name) == kVideoCodecMultiplex) {
+    VideoSendStream::Config::EncoderSettings associated_codec_settings =
+        settings;
+    associated_codec_settings.payload_name =
+        CodecTypeToPayloadString(kVideoCodecVP9);
+    if (!SetupCodec(config, associated_codec_settings, streams, nack_enabled,
+                    codec, bitrate_allocator)) {
       RTC_LOG(LS_ERROR) << "Failed to create stereo encoder configuration.";
       return false;
     }
@@ -43,7 +46,8 @@
   }
 
   *codec =
-      VideoEncoderConfigToVideoCodec(config, streams, nack_enabled);
+      VideoEncoderConfigToVideoCodec(config, streams, settings.payload_name,
+                                     settings.payload_type, nack_enabled);
   *bitrate_allocator = CreateBitrateAllocator(*codec);
 
   return true;
@@ -69,6 +73,8 @@
 VideoCodec VideoCodecInitializer::VideoEncoderConfigToVideoCodec(
     const VideoEncoderConfig& config,
     const std::vector<VideoStream>& streams,
+    const std::string& payload_name,
+    int payload_type,
     bool nack_enabled) {
   static const int kEncoderMinBitrateKbps = 30;
   RTC_DCHECK(!streams.empty());
@@ -76,7 +82,7 @@
 
   VideoCodec video_codec;
   memset(&video_codec, 0, sizeof(video_codec));
-  video_codec.codecType = config.codec_type;
+  video_codec.codecType = PayloadStringToCodecType(payload_name);
 
   switch (config.content_type) {
     case VideoEncoderConfig::ContentType::kRealtimeVideo:
@@ -149,9 +155,7 @@
       break;
   }
 
-  // TODO(nisse): The plType field should be deleted. Luckily, our
-  // callers don't need it.
-  video_codec.plType = 0;
+  video_codec.plType = payload_type;
   video_codec.numberOfSimulcastStreams =
       static_cast<unsigned char>(streams.size());
   video_codec.minBitrate = streams[0].min_bitrate_bps / 1000;