Handle AV1 without DependencyDescriptor.

Bug: webrtc:12221
Change-Id: I757c9407d71131a15e5d6b274e16c7a639512761
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/196080
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Lahiru Ginnaliya Gamathige <glahiru@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32729}
diff --git a/modules/video_coding/rtp_frame_reference_finder.cc b/modules/video_coding/rtp_frame_reference_finder.cc
index 13e1fe3..3084b5b 100644
--- a/modules/video_coding/rtp_frame_reference_finder.cc
+++ b/modules/video_coding/rtp_frame_reference_finder.cc
@@ -88,10 +88,6 @@
 
       return GetRefFinderAs<RtpVp9RefFinder>().ManageFrame(std::move(frame));
     }
-    case kVideoCodecH264: {
-      return GetRefFinderAs<RtpSeqNumOnlyRefFinder>().ManageFrame(
-          std::move(frame));
-    }
     case kVideoCodecGeneric: {
       if (auto* generic_header = absl::get_if<RTPVideoHeaderLegacyGeneric>(
               &video_header.video_type_header)) {
@@ -103,7 +99,8 @@
           std::move(frame));
     }
     default: {
-      RTC_CHECK_NOTREACHED();
+      return GetRefFinderAs<RtpSeqNumOnlyRefFinder>().ManageFrame(
+          std::move(frame));
     }
   }
 }
diff --git a/modules/video_coding/rtp_frame_reference_finder_unittest.cc b/modules/video_coding/rtp_frame_reference_finder_unittest.cc
index 0c08ddd..4cfb559 100644
--- a/modules/video_coding/rtp_frame_reference_finder_unittest.cc
+++ b/modules/video_coding/rtp_frame_reference_finder_unittest.cc
@@ -1491,5 +1491,17 @@
   CheckReferencesH264(sn + 7, sn + 3);
 }
 
+TEST_F(TestRtpFrameReferenceFinder, Av1FrameNoDependencyDescriptor) {
+  uint16_t sn = 0xFFFF;
+  std::unique_ptr<RtpFrameObject> frame =
+      CreateFrame(/*seq_num_start=*/sn, /*seq_num_end=*/sn, /*keyframe=*/true,
+                  kVideoCodecAV1, RTPVideoTypeHeader());
+
+  reference_finder_->ManageFrame(std::move(frame));
+
+  ASSERT_EQ(1UL, frames_from_callback_.size());
+  CheckReferencesGeneric(sn);
+}
+
 }  // namespace video_coding
 }  // namespace webrtc