Callback changes to media transport interface:

1) allow multiple target rate observers
2) add getter for overhead
3) add getter for target rate
4) add callback for network route changed.


Bug: webrtc:9719
Change-Id: I06518cd9aed0ebabd204a7f6af3b86f51fd694e0
Reviewed-on: https://webrtc-review.googlesource.com/c/109940
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Reviewed-by: Anton Sukhanov <sukhanov@webrtc.org>
Reviewed-by: Bjorn Mellem <mellem@webrtc.org>
Commit-Queue: Peter Slatala <psla@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25572}

api/DEPS

@@ -98,6 +98,7 @@ specific_include_rules = {
 
   "media_transport_interface\.h": [
     "+rtc_base/copyonwritebuffer.h",  # As used by datachannelinterface.h
+    "+rtc_base/networkroute.h"
   ],
 
   "peerconnectionfactoryproxy\.h": [

api/media_transport_interface.cc

@@ -103,4 +103,25 @@ MediaTransportFactory::CreateMediaTransport(
   return std::unique_ptr<MediaTransportInterface>(nullptr);
 }
 
+absl::optional<TargetTransferRate>
+MediaTransportInterface::GetLatestTargetTransferRate() {
+  return absl::nullopt;
+}
+
+void MediaTransportInterface::SetNetworkChangeCallback(
+    MediaTransportNetworkChangeCallback* callback) {}
+
+void MediaTransportInterface::RemoveTargetTransferRateObserver(
+    webrtc::TargetTransferRateObserver* observer) {}
+
+void MediaTransportInterface::SetTargetTransferRateObserver(
+    webrtc::TargetTransferRateObserver* observer) {}
+
+void MediaTransportInterface::AddTargetTransferRateObserver(
+    webrtc::TargetTransferRateObserver* observer) {}
+
+size_t MediaTransportInterface::GetAudioPacketOverhead() const {
+  return 0;
+}
+
 }  // namespace webrtc

api/media_transport_interface.h

@@ -29,6 +29,7 @@
 #include "api/video/encoded_image.h"
 #include "common_types.h"  // NOLINT(build/include)
 #include "rtc_base/copyonwritebuffer.h"
+#include "rtc_base/networkroute.h"
 
 namespace rtc {
 class PacketTransportInternal;
@@ -139,6 +140,16 @@ class MediaTransportEncodedAudioFrame final {
   std::vector<uint8_t> encoded_data_;
 };
 
+// Callback to notify about network route changes.
+class MediaTransportNetworkChangeCallback {
+ public:
+  virtual ~MediaTransportNetworkChangeCallback() = default;
+
+  // Called when the network route is changed, with the new network route.
+  virtual void OnNetworkRouteChanged(
+      const rtc::NetworkRoute& new_network_route) = 0;
+};
+
 // Interface for receiving encoded audio frames from MediaTransportInterface
 // implementations.
 class MediaTransportAudioSinkInterface {
@@ -329,8 +340,41 @@ class MediaTransportInterface {
   // the observer must be unregistered (set to nullptr).
   // A newly registered observer will be called back with the latest recorded
   // target rate, if available.
+  // TODO(psla): This method will be removed, in favor of
+  // AddTargetTransferRateObserver.
   virtual void SetTargetTransferRateObserver(
-      webrtc::TargetTransferRateObserver* observer) = 0;
+      TargetTransferRateObserver* observer);
+
+  // Adds a target bitrate observer. Before media transport is destructed
+  // the observer must be unregistered (by calling
+  // RemoveTargetTransferRateObserver).
+  // A newly registered observer will be called back with the latest recorded
+  // target rate, if available.
+  virtual void AddTargetTransferRateObserver(
+      webrtc::TargetTransferRateObserver* observer);
+
+  // Removes an existing |observer| from observers. If observer was never
+  // registered, an error is logged and method does nothing.
+  virtual void RemoveTargetTransferRateObserver(
+      webrtc::TargetTransferRateObserver* observer);
+
+  // Returns the last known target transfer rate as reported to the above
+  // observers.
+  virtual absl::optional<TargetTransferRate> GetLatestTargetTransferRate();
+
+  // Gets the audio packet overhead in bytes. Returned overhead does not include
+  // transport overhead (ipv4/6, turn channeldata, tcp/udp, etc.).
+  // If the transport is capable of fusing packets together, this overhead
+  // might not be a very accurate number.
+  virtual size_t GetAudioPacketOverhead() const;
+
+  // Sets an observer for network change events. If the network route is already
+  // established when the callback is set, |callback| will be called immediately
+  // with the current network route.
+  // Before media transport is destroyed, the callback must be unregistered by
+  // setting it to nullptr.
+  virtual void SetNetworkChangeCallback(
+      MediaTransportNetworkChangeCallback* callback);
 
   // Sets a state observer callback. Before media transport is destroyed, the
   // callback must be unregistered by setting it to nullptr.