Move MediaTransportInterface out of the libjingle_peerconnection_api target

And move related files into api/transport/ and api/transport/media/.
The moved files are unchanged, except that
congestion_control_interface.h and datagram_transport_interface.h
no longer include media_transport_interface.h, instead, they forward
declare the few MediaTransport* types they reference.

Bug: webrtc:8733
Change-Id: I4f4000d0d111f10d15a54c99af27ec26c46ae652
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/152482
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Bjorn Mellem <mellem@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29178}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index a4cd2bc..fc7121c 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -114,7 +114,6 @@
     "crypto_params.h",
     "data_channel_interface.cc",
     "data_channel_interface.h",
-    "data_channel_transport_interface.cc",
     "data_channel_transport_interface.h",
     "datagram_transport_interface.h",
     "dtls_transport_interface.cc",
@@ -130,9 +129,7 @@
     "media_stream_interface.h",
     "media_stream_proxy.h",
     "media_stream_track_proxy.h",
-    "media_transport_config.cc",
     "media_transport_config.h",
-    "media_transport_interface.cc",
     "media_transport_interface.h",
     "notifier.h",
     "packet_socket_factory.h",
@@ -175,8 +172,10 @@
     "rtc_event_log",
     "task_queue",
     "transport:bitrate_settings",
+    "transport:datagram_transport_interface",
     "transport:network_control",
     "transport/media:audio_interfaces",
+    "transport/media:media_transport_interface",
     "transport/media:video_interfaces",
     "transport/rtp:rtp_source",
     "units:data_rate",
@@ -256,6 +255,7 @@
     "../test:test_common",
     "../test:video_test_common",
     "transport:network_control",
+    "transport/media:media_transport_interface",
     "video_codecs:video_codecs_api",
   ]
 }
@@ -350,6 +350,7 @@
     "rtc_event_log",
     "task_queue",
     "transport:network_control",
+    "transport/media:media_transport_interface",
     "units:time_delta",
     "video_codecs:video_codecs_api",
     "//third_party/abseil-cpp/absl/memory",
@@ -873,8 +874,9 @@
     ]
 
     deps = [
-      ":libjingle_peerconnection_api",
       "../rtc_base:checks",
+      "transport:datagram_transport_interface",
+      "transport/media:media_transport_interface",
       "//third_party/abseil-cpp/absl/algorithm:container",
       "//third_party/abseil-cpp/absl/memory",
     ]
@@ -889,9 +891,10 @@
     ]
 
     deps = [
-      ":libjingle_peerconnection_api",
       "../rtc_base",
       "../rtc_base:checks",
+      "transport:datagram_transport_interface",
+      "transport/media:media_transport_interface",
       "//third_party/abseil-cpp/absl/algorithm:container",
       "//third_party/abseil-cpp/absl/memory",
     ]