For VP9 assume max number of spatial layers to simulate generic descriptor

VP9 allows to increase number of spatial layers on delta frame, which
is not supported by dependency descriptor.
Thus to generate DD compatible generic header, simulator would set max
number of spatial layers, while number of active spatial layers would be
communicated with active_decode_target bitmask

Bug: webrtc:14042
Change-Id: I4da63fa7c38b0f17758a7a6243640f444470b40c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/265164
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37151}

call/rtp_video_sender.cc

diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index 1930036..1f55eb8 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -378,9 +378,6 @@
           field_trials_.Lookup("WebRTC-Video-UseFrameRateForOverhead"),
           "Enabled")),
       has_packet_feedback_(TransportSeqNumExtensionConfigured(rtp_config)),
-      simulate_generic_structure_(absl::StartsWith(
-          field_trials_.Lookup("WebRTC-GenericCodecDependencyDescriptor"),
-          "Enabled")),
       active_(false),
       fec_controller_(std::move(fec_controller)),
       fec_allowed_(true),
@@ -603,32 +600,10 @@
     RTPSenderVideo& sender_video = *rtp_streams_[stream_index].sender_video;
     if (codec_specific_info && codec_specific_info->template_structure) {
       sender_video.SetVideoStructure(&*codec_specific_info->template_structure);
-    } else if (codec_specific_info &&
-               codec_specific_info->codecType == kVideoCodecVP8) {
-      FrameDependencyStructure structure =
-          RtpPayloadParams::MinimalisticStructure(/*num_spatial_layers=*/1,
-                                                  kMaxTemporalStreams);
-      sender_video.SetVideoStructure(&structure);
-    } else if (codec_specific_info &&
-               codec_specific_info->codecType == kVideoCodecVP9) {
-      const CodecSpecificInfoVP9& vp9 = codec_specific_info->codecSpecific.VP9;
-
-      FrameDependencyStructure structure =
-          RtpPayloadParams::MinimalisticStructure(vp9.num_spatial_layers,
-                                                  kMaxTemporalStreams);
-      if (vp9.ss_data_available && vp9.spatial_layer_resolution_present) {
-        for (size_t i = 0; i < vp9.num_spatial_layers; ++i) {
-          structure.resolutions.emplace_back(vp9.width[i], vp9.height[i]);
-        }
-      }
-      sender_video.SetVideoStructure(&structure);
-    } else if (simulate_generic_structure_ && codec_specific_info &&
-               codec_specific_info->codecType == kVideoCodecGeneric) {
-      FrameDependencyStructure structure =
-          RtpPayloadParams::MinimalisticStructure(
-              /*num_spatial_layers=*/1,
-              /*num_temporal_layers=*/1);
-      sender_video.SetVideoStructure(&structure);
+    } else if (absl::optional<FrameDependencyStructure> structure =
+                   params_[stream_index].GenericStructure(
+                       codec_specific_info)) {
+      sender_video.SetVideoStructure(&*structure);
     } else {
       sender_video.SetVideoStructure(nullptr);
     }