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diff --git a/third_party/libwebrtc/api/voip/voip_base.h b/third_party/libwebrtc/api/voip/voip_base.h
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+/*
+ *  Copyright (c) 2020 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_VOIP_VOIP_BASE_H_
+#define API_VOIP_VOIP_BASE_H_
+
+#include "absl/base/attributes.h"
+#include "absl/types/optional.h"
+
+namespace webrtc {
+
+class Transport;
+
+// VoipBase interface
+//
+// VoipBase provides a management interface on a media session using a
+// concept called 'channel'.  A channel represents an interface handle
+// for application to request various media session operations.  This
+// notion of channel is used throughout other interfaces as well.
+//
+// Underneath the interface, a channel id is mapped into an audio session
+// object that is capable of sending and receiving a single RTP stream with
+// another media endpoint.  It's possible to create and use multiple active
+// channels simultaneously which would mean that particular application
+// session has RTP streams with multiple remote endpoints.
+//
+// A typical example for the usage context is outlined in VoipEngine
+// header file.
+
+enum class ChannelId : int {};
+
+enum class ABSL_MUST_USE_RESULT VoipResult {
+  // kOk indicates the function was successfully invoked with no error.
+  kOk,
+  // kInvalidArgument indicates the caller specified an invalid argument, such
+  // as an invalid ChannelId.
+  kInvalidArgument,
+  // kFailedPrecondition indicates that the operation was failed due to not
+  // satisfying prerequisite such as not setting codec type before sending.
+  kFailedPrecondition,
+  // kInternal is used to indicate various internal failures that are not the
+  // caller's fault. Further detail is commented on each function that uses this
+  // return value.
+  kInternal,
+};
+
+class VoipBase {
+ public:
+  // Creates a channel.
+  // Each channel handle maps into one audio media session where each has
+  // its own separate module for send/receive rtp packet with one peer.
+  // Caller must set `transport`, webrtc::Transport callback pointer to
+  // receive rtp/rtcp packets from corresponding media session in VoIP engine.
+  // VoipEngine framework expects applications to handle network I/O directly
+  // and injection for incoming RTP from remote endpoint is handled via
+  // VoipNetwork interface. `local_ssrc` is optional and when local_ssrc is not
+  // set, some random value will be used by voip engine.
+  // Returns a ChannelId created for caller to handle subsequent Channel
+  // operations.
+  virtual ChannelId CreateChannel(Transport* transport,
+                                  absl::optional<uint32_t> local_ssrc) = 0;
+
+  // Releases `channel_id` that no longer has any use.
+  // Returns following VoipResult;
+  //  kOk - `channel_id` is released.
+  //  kInvalidArgument - `channel_id` is invalid.
+  //  kInternal - Fails to stop audio output device.
+  virtual VoipResult ReleaseChannel(ChannelId channel_id) = 0;
+
+  // Starts sending on `channel_id`. This starts microphone if not started yet.
+  // Returns following VoipResult;
+  //  kOk - Channel successfully started to send.
+  //  kInvalidArgument - `channel_id` is invalid.
+  //  kFailedPrecondition - Missing prerequisite on VoipCodec::SetSendCodec.
+  //  kInternal - initialization has failed on selected microphone.
+  virtual VoipResult StartSend(ChannelId channel_id) = 0;
+
+  // Stops sending on `channel_id`. If this is the last active channel, it will
+  // stop microphone input from underlying audio platform layer.
+  // Returns following VoipResult;
+  //  kOk - Channel successfully stopped to send.
+  //  kInvalidArgument - `channel_id` is invalid.
+  //  kInternal - Failed to stop the active microphone device.
+  virtual VoipResult StopSend(ChannelId channel_id) = 0;
+
+  // Starts playing on speaker device for `channel_id`.
+  // This will start underlying platform speaker device if not started.
+  // Returns following VoipResult;
+  //  kOk - Channel successfully started to play out.
+  //  kInvalidArgument - `channel_id` is invalid.
+  //  kFailedPrecondition - Missing prerequisite on VoipCodec::SetReceiveCodecs.
+  //  kInternal - Failed to initializate the selected speaker device.
+  virtual VoipResult StartPlayout(ChannelId channel_id) = 0;
+
+  // Stops playing on speaker device for `channel_id`.
+  // Returns following VoipResult;
+  //  kOk - Channel successfully stopped t play out.
+  //  kInvalidArgument - `channel_id` is invalid.
+  virtual VoipResult StopPlayout(ChannelId channel_id) = 0;
+
+ protected:
+  virtual ~VoipBase() = default;
+};
+
+}  // namespace webrtc
+
+#endif  // API_VOIP_VOIP_BASE_H_