Move rtc_base/network/ecn_marking.h to api/transport

For now, old file forward include api/transport/ecn_marking.h
Done in preparation for more usage of this enum when handling received
RFC8888 feedback.

Bug: webrtc:42225697
Change-Id: I022c2b7f1e7f986b24aa32b8911ad67c6640a5c0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/366440
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43282}

api/transport/BUILD.gn

@@ -28,6 +28,11 @@ rtc_library("bandwidth_estimation_settings") {
   deps = [ "../../rtc_base/system:rtc_export" ]
 }
 
+rtc_source_set("ecn_marking") {
+  visibility = [ "*" ]
+  sources = [ "ecn_marking.h" ]
+}
+
 rtc_source_set("enums") {
   visibility = [ "*" ]
   sources = [ "enums.h" ]

api/transport/ecn_marking.h

@@ -0,0 +1,42 @@
+/*
+ *  Copyright 2024 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_TRANSPORT_ECN_MARKING_H_
+#define API_TRANSPORT_ECN_MARKING_H_
+
+namespace webrtc {
+
+// TODO: bugs.webrtc.org/42225697 - L4S support is slowly being developed.
+// Help is appreciated.
+
+// L4S Explicit Congestion Notification (ECN) .
+// https://www.rfc-editor.org/rfc/rfc9331.html ECT stands for ECN-Capable
+// Transport and CE stands for Congestion Experienced.
+
+// RFC-3168, Section 5
+// +-----+-----+
+// | ECN FIELD |
+// +-----+-----+
+//   ECT   CE         [Obsolete] RFC 2481 names for the ECN bits.
+//    0     0         Not-ECT
+//    0     1         ECT(1)
+//    1     0         ECT(0)
+//    1     1         CE
+
+enum class EcnMarking {
+  kNotEct = 0,  // Not ECN-Capable Transport
+  kEct1 = 1,    // ECN-Capable Transport
+  kEct0 = 2,    // Not used by L4s (or webrtc.)
+  kCe = 3,      // Congestion experienced
+};
+
+}  // namespace webrtc
+
+#endif  // API_TRANSPORT_ECN_MARKING_H_

rtc_base/network/BUILD.gn

@@ -19,6 +19,7 @@ rtc_library("sent_packet") {
 rtc_source_set("ecn_marking") {
   visibility = [ "*" ]
   sources = [ "ecn_marking.h" ]
+  deps = [ "../../api/transport:ecn_marking" ]
 }
 
 rtc_library("received_packet") {

rtc_base/network/ecn_marking.h

@@ -7,36 +7,14 @@
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
-
 #ifndef RTC_BASE_NETWORK_ECN_MARKING_H_
 #define RTC_BASE_NETWORK_ECN_MARKING_H_
 
+// // TODO: bugs.webrtc.org/42225697 - delete this file.
+#include "api/transport/ecn_marking.h"
+
 namespace rtc {
-
+using ::webrtc::EcnMarking;
-// TODO(https://bugs.webrtc.org/15368): L4S support is slowly being developed.
-// Help is appreciated.
-
-// L4S Explicit Congestion Notification (ECN) .
-// https://www.rfc-editor.org/rfc/rfc9331.html ECT stands for ECN-Capable
-// Transport and CE stands for Congestion Experienced.
-
-// RFC-3168, Section 5
-// +-----+-----+
-// | ECN FIELD |
-// +-----+-----+
-//   ECT   CE         [Obsolete] RFC 2481 names for the ECN bits.
-//    0     0         Not-ECT
-//    0     1         ECT(1)
-//    1     0         ECT(0)
-//    1     1         CE
-
-enum class EcnMarking {
-  kNotEct = 0,  // Not ECN-Capable Transport
-  kEct1 = 1,    // ECN-Capable Transport
-  kEct0 = 2,    // Not used by L4s (or webrtc.)
-  kCe = 3,      // Congestion experienced
-};
-
 }  // namespace rtc
 
 #endif  // RTC_BASE_NETWORK_ECN_MARKING_H_