Remove effectively dead code for allow_codec_switching

Bug: webrtc:11341
Change-Id: I88e3c1059f5ebcc9d693c0719534aaacd4b9199b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/324283
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40990}

api/peer_connection_interface.h

@@ -662,6 +662,7 @@ class RTC_EXPORT PeerConnectionInterface : public rtc::RefCountInterface {
     bool enable_implicit_rollback = false;
 
     // Whether network condition based codec switching is allowed.
+    // TODO(bugs.webrtc.org/11341): Remove this unsupported config value.
     absl::optional<bool> allow_codec_switching;
 
     // The delay before doing a usage histogram report for long-lived

media/base/fake_media_engine.h

@@ -741,7 +741,6 @@ class FakeVideoMediaSendChannel
   void SetSsrcListChangedCallback(
       absl::AnyInvocable<void(const std::set<uint32_t>&)> callback) override {}
 
-  void SetVideoCodecSwitchingEnabled(bool enabled) override {}
   bool SendCodecHasLntf() const override { return false; }
   bool SendCodecHasNack() const override { return false; }
   absl::optional<int> SendCodecRtxTime() const override {

media/base/media_channel.h

@@ -949,8 +949,6 @@ class VideoMediaSendChannelInterface : public MediaSendChannelInterface {
   // Cause generation of a keyframe for `ssrc` on a sending channel.
   virtual void GenerateSendKeyFrame(uint32_t ssrc,
                                     const std::vector<std::string>& rids) = 0;
-  // Enable network condition based codec switching.
-  virtual void SetVideoCodecSwitchingEnabled(bool enabled) = 0;
   virtual bool GetStats(VideoMediaSendInfo* stats) = 0;
   // This fills the "bitrate parts" (rtx, video bitrate) of the
   // BandwidthEstimationInfo, since that part that isn't possible to get

media/engine/webrtc_video_engine.cc

@@ -1674,14 +1674,6 @@ void WebRtcVideoSendChannel::SetEncoderSelector(
   }
 }
 
-void WebRtcVideoSendChannel::SetVideoCodecSwitchingEnabled(bool enabled) {
-  RTC_DCHECK_RUN_ON(&thread_checker_);
-  allow_codec_switching_ = enabled;
-  if (allow_codec_switching_) {
-    RTC_LOG(LS_INFO) << "Encoder switching enabled.";
-  }
-}
-
 WebRtcVideoSendChannel::WebRtcVideoSendStream::VideoSendStreamParameters::
     VideoSendStreamParameters(
         webrtc::VideoSendStream::Config config,

media/engine/webrtc_video_engine.h

@@ -225,8 +225,6 @@ class WebRtcVideoSendChannel : public MediaChannelUtil,
                           webrtc::VideoEncoderFactory::EncoderSelectorInterface*
                               encoder_selector) override;
 
-  void SetVideoCodecSwitchingEnabled(bool enabled) override;
-
   void SetSendCodecChangedCallback(
       absl::AnyInvocable<void()> callback) override {
     send_codec_changed_callback_ = std::move(callback);
@@ -549,11 +547,6 @@ class WebRtcVideoSendChannel : public MediaChannelUtil,
   rtc::scoped_refptr<webrtc::FrameTransformerInterface>
       unsignaled_frame_transformer_ RTC_GUARDED_BY(thread_checker_);
 
-  // TODO(bugs.webrtc.org/11341): Remove this and relevant PC API. Presence
-  // of multiple negotiated codecs allows generic encoder fallback on failures.
-  // Presence of EncoderSelector allows switching to specific encoders.
-  bool allow_codec_switching_ = false;
-
   // RTP parameters that need to be set when creating a video receive stream.
   // Only used in Receiver mode - in Both mode, it reads those things from the
   // codec.

media/engine/webrtc_video_engine_unittest.cc

@@ -2660,7 +2660,6 @@ TEST_F(WebRtcVideoChannelBaseTest, SendCodecIsMovedToFrontInRtpParameters) {
   parameters.codecs.push_back(GetEngineCodec("VP9"));
   parameters.codecs.push_back(GetEngineCodec("VP8"));
   EXPECT_TRUE(send_channel_->SetSenderParameters(parameters));
-  send_channel_->SetVideoCodecSwitchingEnabled(true);
 
   auto send_codecs = send_channel_->GetRtpSendParameters(kSsrc).codecs;
   ASSERT_EQ(send_codecs.size(), 2u);

pc/peer_connection.cc

@@ -1676,27 +1676,6 @@ RTCError PeerConnection::SetConfiguration(
                          "Failed to apply configuration to PortAllocator.");
   }
 
-  if (modified_config.allow_codec_switching.has_value()) {
-    std::vector<cricket::VideoMediaSendChannelInterface*> channels;
-    for (const auto& transceiver : rtp_manager()->transceivers()->List()) {
-      if (transceiver->media_type() != cricket::MEDIA_TYPE_VIDEO)
-        continue;
-
-      auto* video_channel = transceiver->internal()->channel();
-      if (video_channel)
-        channels.push_back(
-            static_cast<cricket::VideoMediaSendChannelInterface*>(
-                video_channel->media_send_channel()));
-    }
-
-    worker_thread()->BlockingCall(
-        [channels = std::move(channels),
-         allow_codec_switching = *modified_config.allow_codec_switching]() {
-          for (auto* ch : channels)
-            ch->SetVideoCodecSwitchingEnabled(allow_codec_switching);
-        });
-  }
-
   configuration_ = modified_config;
   return RTCError::OK();
 }