Introduce MediaTransportConfig

Currently we pass media_transport from PeerConnection to media layers. The goal of this change is to replace media_transport with struct MediaTransportCondif, which will enable adding different transports (i.e. we plan to add DatagramTransport) as well as other media-transport related settings without changing 100s of files.

TODO: In the future we should consider also adding rtp_transport in the same config, but it will require a bit more work, so I did not include it in the same change.


Bug: webrtc:9719
Change-Id: Ie31e1faa3ed9e6beefe30a3da208130509ce00cd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/137181
Commit-Queue: Anton Sukhanov <sukhanov@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Bjorn Mellem <mellem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28016}
diff --git a/audio/audio_send_stream_unittest.cc b/audio/audio_send_stream_unittest.cc
index 5ddc5e1..4531755 100644
--- a/audio/audio_send_stream_unittest.cc
+++ b/audio/audio_send_stream_unittest.cc
@@ -136,7 +136,7 @@
   ConfigHelper(bool audio_bwe_enabled, bool expect_set_encoder_call)
       : clock_(1000000),
         task_queue_factory_(CreateDefaultTaskQueueFactory()),
-        stream_config_(/*send_transport=*/nullptr, /*media_transport=*/nullptr),
+        stream_config_(/*send_transport=*/nullptr, MediaTransportConfig()),
         audio_processing_(new rtc::RefCountedObject<MockAudioProcessing>()),
         bitrate_allocator_(&clock_, &limit_observer_),
         worker_queue_(task_queue_factory_->CreateTaskQueue(
@@ -321,7 +321,7 @@
 
 TEST(AudioSendStreamTest, ConfigToString) {
   AudioSendStream::Config config(/*send_transport=*/nullptr,
-                                 /*media_transport=*/nullptr);
+                                 MediaTransportConfig());
   config.rtp.ssrc = kSsrc;
   config.rtp.c_name = kCName;
   config.min_bitrate_bps = 12000;
@@ -340,7 +340,7 @@
       "{rtp: {ssrc: 1234, extmap-allow-mixed: true, extensions: [{uri: "
       "urn:ietf:params:rtp-hdrext:ssrc-audio-level, id: 2}], "
       "c_name: foo_name}, rtcp_report_interval_ms: 2500, "
-      "send_transport: null, media_transport: null, "
+      "send_transport: null, media_transport_config: {media_transport: null}, "
       "min_bitrate_bps: 12000, max_bitrate_bps: 34000, "
       "send_codec_spec: {nack_enabled: true, transport_cc_enabled: false, "
       "cng_payload_type: 42, payload_type: 103, "