Revert "Reland "Ensure RTCRtpSenders are always created with one encoding""

This reverts commit fc5d627cef.

Reason for revert: Breaks upstream WPT tests

Original change's description:
> Reland "Ensure RTCRtpSenders are always created with one encoding"
>
> This is a reland of commit b8023690d9
>
> Original change's description:
> > Ensure RTCRtpSenders are always created with one encoding
> >
> > It is possible to have AddTransceiver calls with an empty array
> > of encodings or AddTrack calls. In both cases, before negotiation,
> > the sender's encodings array would be empty and it was not possible
> > to update any value.
> >
> > Now, a default entry should be created in those cases, allowing to
> > update the configuration before negotiation.
> >
> > Bug: webrtc:10567
> > Change-Id: I1271e2965e1a97c1e472451e0ab8867fc24f6c2b
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/290994
> > Auto-Submit: Florent Castelli <orphis@webrtc.org>
> > Reviewed-by: Henrik Boström <hbos@webrtc.org>
> > Commit-Queue: Florent Castelli <orphis@webrtc.org>
> > Cr-Commit-Position: refs/heads/main@{#39126}
>
> Bug: webrtc:10567
> Change-Id: I2d52fa5b1d7cfdc9dce279fcf9faf1e0129c9008
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/291140
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Florent Castelli <orphis@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#39145}

Bug: webrtc:10567
Change-Id: If9b5adb5debb7c87a15662a8d0f232405a0e8136
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/291221
Auto-Submit: Evan Shrubsole <eshr@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39147}

pc/peer_connection.cc

@@ -1096,11 +1096,6 @@ PeerConnection::AddTransceiver(
     }
   }
 
-  // If no encoding parameters were provided, a default entry is created.
-  if (parameters.encodings.empty()) {
-    parameters.encodings.push_back({});
-  }
-
   if (UnimplementedRtpParameterHasValue(parameters)) {
     LOG_AND_RETURN_ERROR(
         RTCErrorType::UNSUPPORTED_PARAMETER,

pc/peer_connection_integrationtest.cc

@@ -2834,14 +2834,6 @@ TEST_P(PeerConnectionIntegrationTest, UnsignaledSsrcGetParametersVideo) {
   EXPECT_TRUE(parameters.encodings[0].ssrc.has_value());
 }
 
-TEST_P(PeerConnectionIntegrationTest,
-       GetParametersHasEncodingsBeforeNegotiation) {
-  ASSERT_TRUE(CreatePeerConnectionWrappers());
-  auto sender = caller()->AddTrack(caller()->CreateLocalVideoTrack());
-  auto parameters = sender->GetParameters();
-  EXPECT_EQ(parameters.encodings.size(), 1u);
-}
-
 // Test that if a track is removed and added again with a different stream ID,
 // the new stream ID is successfully communicated in SDP and media continues to
 // flow end-to-end.
@@ -3418,28 +3410,6 @@ TEST_F(PeerConnectionIntegrationTestUnifiedPlan,
   }
 }
 
-TEST_F(PeerConnectionIntegrationTestUnifiedPlan,
-       GetParametersHasEncodingsBeforeNegotiation) {
-  ASSERT_TRUE(CreatePeerConnectionWrappers());
-  auto result = caller()->pc()->AddTransceiver(cricket::MEDIA_TYPE_VIDEO);
-  auto transceiver = result.MoveValue();
-  auto parameters = transceiver->sender()->GetParameters();
-  EXPECT_EQ(parameters.encodings.size(), 1u);
-}
-
-TEST_F(PeerConnectionIntegrationTestUnifiedPlan,
-       GetParametersHasInitEncodingsBeforeNegotiation) {
-  ASSERT_TRUE(CreatePeerConnectionWrappers());
-  RtpTransceiverInit init;
-  init.send_encodings.push_back({});
-  init.send_encodings[0].max_bitrate_bps = 12345;
-  auto result = caller()->pc()->AddTransceiver(cricket::MEDIA_TYPE_VIDEO, init);
-  auto transceiver = result.MoveValue();
-  auto parameters = transceiver->sender()->GetParameters();
-  ASSERT_EQ(parameters.encodings.size(), 1u);
-  EXPECT_EQ(parameters.encodings[0].max_bitrate_bps, 12345);
-}
-
 INSTANTIATE_TEST_SUITE_P(
     PeerConnectionIntegrationTest,
     PeerConnectionIntegrationTest,

pc/rtp_transmission_manager.cc

@@ -150,11 +150,10 @@ RtpTransmissionManager::AddTrackPlanB(
       (track->kind() == MediaStreamTrackInterface::kAudioKind
            ? cricket::MEDIA_TYPE_AUDIO
            : cricket::MEDIA_TYPE_VIDEO);
-  auto new_sender = CreateSender(
+  auto new_sender =
-      media_type, track->id(), track, adjusted_stream_ids,
+      CreateSender(media_type, track->id(), track, adjusted_stream_ids,
-      init_send_encodings
+                   init_send_encodings ? *init_send_encodings
-          ? *init_send_encodings
+                                       : std::vector<RtpEncodingParameters>());
-          : std::vector<RtpEncodingParameters>(1, RtpEncodingParameters{}));
   if (track->kind() == MediaStreamTrackInterface::kAudioKind) {
     new_sender->internal()->SetMediaChannel(voice_media_send_channel());
     GetAudioTransceiver()->internal()->AddSender(new_sender);
@@ -218,11 +217,10 @@ RtpTransmissionManager::AddTrackUnifiedPlan(
     if (FindSenderById(sender_id)) {
       sender_id = rtc::CreateRandomUuid();
     }
-    auto sender = CreateSender(
+    auto sender = CreateSender(media_type, sender_id, track, stream_ids,
-        media_type, sender_id, track, stream_ids,
+                               init_send_encodings
-        init_send_encodings
+                                   ? *init_send_encodings
-            ? *init_send_encodings
+                                   : std::vector<RtpEncodingParameters>());
-            : std::vector<RtpEncodingParameters>(1, RtpEncodingParameters{}));
     auto receiver = CreateReceiver(media_type, rtc::CreateRandomUuid());
     transceiver = CreateAndAddTransceiver(sender, receiver);
     transceiver->internal()->set_created_by_addtrack(true);
@@ -413,7 +411,7 @@ void RtpTransmissionManager::AddAudioTrack(AudioTrackInterface* track,
   // Normal case; we've never seen this track before.
   auto new_sender = CreateSender(cricket::MEDIA_TYPE_AUDIO, track->id(),
                                  rtc::scoped_refptr<AudioTrackInterface>(track),
-                                 {stream->id()}, {{}});
+                                 {stream->id()}, {});
   new_sender->internal()->SetMediaChannel(voice_media_send_channel());
   GetAudioTransceiver()->internal()->AddSender(new_sender);
   // If the sender has already been configured in SDP, we call SetSsrc,
@@ -460,7 +458,7 @@ void RtpTransmissionManager::AddVideoTrack(VideoTrackInterface* track,
   // Normal case; we've never seen this track before.
   auto new_sender = CreateSender(cricket::MEDIA_TYPE_VIDEO, track->id(),
                                  rtc::scoped_refptr<VideoTrackInterface>(track),
-                                 {stream->id()}, {{}});
+                                 {stream->id()}, {});
   new_sender->internal()->SetMediaChannel(video_media_send_channel());
   GetVideoTransceiver()->internal()->AddSender(new_sender);
   const RtpSenderInfo* sender_info =