Eliminate channel.h from rtp_transmission_manager.cc

This also hides the existence of the classes VideoChannel and
VoiceChannel from anything that does not include "channel.h".

Bug: webrtc:13931
Change-Id: I080a692b6acfd5d2d0401ec20d59c3a684eddb05
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/260944
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36746}

pc/BUILD.gn

@@ -118,6 +118,19 @@ rtc_source_set("channel_interface") {
   absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
 }
 
+rtc_source_set("channel_factory_interface") {
+  visibility = [ ":*" ]
+  sources = [ "channel_factory_interface.h" ]
+  deps = [
+    "../api:audio_options_api",
+    "../api/crypto:options",
+    "../api/video:video_bitrate_allocator_factory",
+    "../call:call_interfaces",
+    "../media:rtc_media_base",
+    "../media:rtc_media_config",
+  ]
+}
+
 rtc_source_set("channel_manager") {
   visibility = [ ":*" ]
   sources = [
@@ -126,6 +139,7 @@ rtc_source_set("channel_manager") {
   ]
   deps = [
     ":channel",
+    ":channel_factory_interface",
     ":channel_interface",
     ":session_description",
     "../api:audio_options_api",
@@ -1611,6 +1625,7 @@ rtc_library("rtp_transmission_manager") {
   deps = [
     ":audio_rtp_receiver",
     ":channel",
+    ":channel_interface",
     ":channel_manager",
     ":rtp_receiver",
     ":rtp_receiver_proxy",

pc/channel.h

@@ -158,6 +158,14 @@ class BaseChannel : public ChannelInterface,
   MediaChannel* media_channel() const override {
     return media_channel_.get();
   }
+  VideoMediaChannel* video_media_channel() const override {
+    RTC_CHECK(false) << "Attempt to fetch video channel from non-video";
+    return nullptr;
+  }
+  VoiceMediaChannel* voice_media_channel() const override {
+    RTC_CHECK(false) << "Attempt to fetch voice channel from non-voice";
+    return nullptr;
+  }
 
  protected:
   void set_local_content_direction(webrtc::RtpTransceiverDirection direction)
@@ -364,6 +372,10 @@ class VoiceChannel : public BaseChannel {
     return static_cast<VoiceMediaChannel*>(BaseChannel::media_channel());
   }
 
+  VoiceMediaChannel* voice_media_channel() const override {
+    return static_cast<VoiceMediaChannel*>(media_channel());
+  }
+
   cricket::MediaType media_type() const override {
     return cricket::MEDIA_TYPE_AUDIO;
   }
@@ -406,6 +418,10 @@ class VideoChannel : public BaseChannel {
     return static_cast<VideoMediaChannel*>(BaseChannel::media_channel());
   }
 
+  VideoMediaChannel* video_media_channel() const override {
+    return static_cast<cricket::VideoMediaChannel*>(media_channel());
+  }
+
   cricket::MediaType media_type() const override {
     return cricket::MEDIA_TYPE_VIDEO;
   }

pc/channel_factory_interface.h

@@ -0,0 +1,55 @@
+/*
+ *  Copyright 2004 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 PC_CHANNEL_FACTORY_INTERFACE_H_
+#define PC_CHANNEL_FACTORY_INTERFACE_H_
+
+#include <memory>
+#include <string>
+
+#include "api/audio_options.h"
+#include "api/crypto/crypto_options.h"
+#include "api/video/video_bitrate_allocator_factory.h"
+#include "call/call.h"
+#include "media/base/media_channel.h"
+#include "media/base/media_config.h"
+
+namespace cricket {
+
+class VideoChannel;
+class VoiceChannel;
+
+class ChannelFactoryInterface {
+ public:
+  virtual std::unique_ptr<VideoChannel> CreateVideoChannel(
+      webrtc::Call* call,
+      const MediaConfig& media_config,
+      const std::string& mid,
+      bool srtp_required,
+      const webrtc::CryptoOptions& crypto_options,
+      const VideoOptions& options,
+      webrtc::VideoBitrateAllocatorFactory*
+          video_bitrate_allocator_factory) = 0;
+
+  virtual std::unique_ptr<VoiceChannel> CreateVoiceChannel(
+      webrtc::Call* call,
+      const MediaConfig& media_config,
+      const std::string& mid,
+      bool srtp_required,
+      const webrtc::CryptoOptions& crypto_options,
+      const AudioOptions& options) = 0;
+
+ protected:
+  virtual ~ChannelFactoryInterface() = default;
+};
+
+}  // namespace cricket
+
+#endif  // PC_CHANNEL_FACTORY_INTERFACE_H_

pc/channel_interface.h

@@ -29,8 +29,6 @@ class VideoBitrateAllocatorFactory;
 namespace cricket {
 
 class MediaContentDescription;
-class VideoChannel;
-class VoiceChannel;
 struct MediaConfig;
 
 // A Channel is a construct that groups media streams of the same type
@@ -50,6 +48,10 @@ class ChannelInterface {
   virtual cricket::MediaType media_type() const = 0;
 
   virtual MediaChannel* media_channel() const = 0;
+  // Typecasts of media_channel(). Will cause an exception if the
+  // channel is of the wrong type.
+  virtual VideoMediaChannel* video_media_channel() const = 0;
+  virtual VoiceMediaChannel* voice_media_channel() const = 0;
 
   // Returns a string view for the transport name. Fetching the transport name
   // must be done on the network thread only and note that the lifetime of
@@ -88,30 +90,6 @@ class ChannelInterface {
   virtual bool SetRtpTransport(webrtc::RtpTransportInternal* rtp_transport) = 0;
 };
 
-class ChannelFactoryInterface {
- public:
-  virtual std::unique_ptr<VideoChannel> CreateVideoChannel(
-      webrtc::Call* call,
-      const MediaConfig& media_config,
-      const std::string& mid,
-      bool srtp_required,
-      const webrtc::CryptoOptions& crypto_options,
-      const VideoOptions& options,
-      webrtc::VideoBitrateAllocatorFactory*
-          video_bitrate_allocator_factory) = 0;
-
-  virtual std::unique_ptr<VoiceChannel> CreateVoiceChannel(
-      webrtc::Call* call,
-      const MediaConfig& media_config,
-      const std::string& mid,
-      bool srtp_required,
-      const webrtc::CryptoOptions& crypto_options,
-      const AudioOptions& options) = 0;
-
- protected:
-  virtual ~ChannelFactoryInterface() = default;
-};
-
 }  // namespace cricket
 
 #endif  // PC_CHANNEL_INTERFACE_H_

pc/channel_manager.h

@@ -26,6 +26,7 @@
 #include "media/base/media_channel.h"
 #include "media/base/media_config.h"
 #include "media/base/media_engine.h"
+#include "pc/channel_factory_interface.h"
 #include "pc/channel_interface.h"
 #include "pc/session_description.h"
 #include "rtc_base/system/file_wrapper.h"

pc/rtp_transmission_manager.cc

@@ -17,7 +17,7 @@
 #include "api/peer_connection_interface.h"
 #include "api/rtp_transceiver_direction.h"
 #include "pc/audio_rtp_receiver.h"
-#include "pc/channel.h"
+#include "pc/channel_interface.h"
 #include "pc/stats_collector_interface.h"
 #include "pc/video_rtp_receiver.h"
 #include "rtc_base/checks.h"
@@ -81,10 +81,9 @@ cricket::VoiceMediaChannel* RtpTransmissionManager::voice_media_channel()
     const {
   RTC_DCHECK_RUN_ON(signaling_thread());
   RTC_DCHECK(!IsUnifiedPlan());
-  auto* voice_channel = static_cast<cricket::VoiceChannel*>(
-      GetAudioTransceiver()->internal()->channel());
+  auto* voice_channel = GetAudioTransceiver()->internal()->channel();
   if (voice_channel) {
-    return voice_channel->media_channel();
+    return voice_channel->voice_media_channel();
   } else {
     return nullptr;
   }
@@ -94,10 +93,9 @@ cricket::VideoMediaChannel* RtpTransmissionManager::video_media_channel()
     const {
   RTC_DCHECK_RUN_ON(signaling_thread());
   RTC_DCHECK(!IsUnifiedPlan());
-  auto* video_channel = static_cast<cricket::VideoChannel*>(
-      GetVideoTransceiver()->internal()->channel());
+  auto* video_channel = GetVideoTransceiver()->internal()->channel();
   if (video_channel) {
-    return video_channel->media_channel();
+    return video_channel->video_media_channel();
   } else {
     return nullptr;
   }

pc/test/mock_channel_interface.h

@@ -26,6 +26,8 @@ class MockChannelInterface : public cricket::ChannelInterface {
  public:
   MOCK_METHOD(cricket::MediaType, media_type, (), (const, override));
   MOCK_METHOD(MediaChannel*, media_channel, (), (const, override));
+  MOCK_METHOD(VoiceMediaChannel*, voice_media_channel, (), (const, override));
+  MOCK_METHOD(VideoMediaChannel*, video_media_channel, (), (const, override));
   MOCK_METHOD(absl::string_view, transport_name, (), (const, override));
   MOCK_METHOD(const std::string&, mid, (), (const, override));
   MOCK_METHOD(void, Enable, (bool), (override));