Delete the VideoCodec::plName string.

It holds the same information as codecType, but in different format.

Bug: webrtc:8830
Change-Id: Ia83e2dff4fd9a5ddb489501b7a1fe80759fa4218
Reviewed-on: https://webrtc-review.googlesource.com/56100
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22307}

modules/video_coding/generic_encoder.cc

@@ -68,8 +68,9 @@ int32_t VCMGenericEncoder::InitEncode(const VideoCodec* settings,
 
   if (encoder_->InitEncode(settings, number_of_cores, max_payload_size) != 0) {
     RTC_LOG(LS_ERROR) << "Failed to initialize the encoder associated with "
-                         "payload name: "
-                      << settings->plName;
+                         "codec type: "
+                      << CodecTypeToPayloadString(settings->codecType)
+                      << " (" << settings->codecType <<")";
     return -1;
   }
   vcm_encoded_frame_callback_->Reset();