Remove ImplForTesting function from MediaChannel

It is not used any more.

Bug: webrtc:13931
Change-Id: I266de41abe239907c6d65f4b182a8dc3aacaba3d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/308022
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40234}
diff --git a/media/base/media_channel.h b/media/base/media_channel.h
index f23df8b..ea6384a 100644
--- a/media/base/media_channel.h
+++ b/media/base/media_channel.h
@@ -255,10 +255,6 @@
   // TODO(bugs.webrtc.org/13931): Remove when configuration is more sensible
   virtual void SetSendCodecChangedCallback(
       absl::AnyInvocable<void()> callback) = 0;
-
-  // Get the underlying send/receive implementation channel for testing.
-  // TODO(bugs.webrtc.org/13931): Remove method and the fakes that depend on it.
-  virtual MediaChannel* ImplForTesting() = 0;
 };
 
 class MediaReceiveChannelInterface : public Delayable {
@@ -313,9 +309,6 @@
       uint32_t ssrc,
       rtc::scoped_refptr<webrtc::FrameTransformerInterface>
           frame_transformer) = 0;
-  // Get the underlying send/receive implementation channel for testing.
-  // TODO(bugs.webrtc.org/13931): Remove method and the fakes that depend on it.
-  virtual MediaChannel* ImplForTesting() = 0;
 };
 
 // The stats information is structured as follows:
diff --git a/media/base/media_channel_impl.h b/media/base/media_channel_impl.h
index 66c2f3e..33007d0 100644
--- a/media/base/media_channel_impl.h
+++ b/media/base/media_channel_impl.h
@@ -302,10 +302,6 @@
   bool HasNetworkInterface() const override {
     return MediaChannel::HasNetworkInterface();
   }
-  MediaChannel* ImplForTesting() override {
-    // This class and its subclasses are not interface classes.
-    RTC_CHECK_NOTREACHED();
-  }
 };
 
 // Base class for implementation classes
@@ -379,13 +375,6 @@
                 bool get_and_clear_legacy_stats) override {
     return GetReceiveStats(info, get_and_clear_legacy_stats);
   }
-
- private:
-  // Functions not implemented on this interface
-  MediaChannel* ImplForTesting() override {
-    // This class and its subclasses are not interface classes.
-    RTC_CHECK_NOTREACHED();
-  }
 };
 
 }  // namespace cricket
diff --git a/media/base/media_channel_shim.h b/media/base/media_channel_shim.h
index 335fae2..e4dbee7 100644
--- a/media/base/media_channel_shim.h
+++ b/media/base/media_channel_shim.h
@@ -83,12 +83,6 @@
     }
   }
 
-  // Not really valid for this mode
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
-
   // Implementation of MediaBaseChannelInterface
   cricket::MediaType media_type() const override { return MEDIA_TYPE_AUDIO; }
 
@@ -331,12 +325,6 @@
     }
   }
 
-  // Not really valid for this mode
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
-
   // Implementation of MediaBaseChannelInterface
   cricket::MediaType media_type() const override { return MEDIA_TYPE_VIDEO; }
 
diff --git a/media/engine/webrtc_video_engine.h b/media/engine/webrtc_video_engine.h
index 3635c21..e210f04 100644
--- a/media/engine/webrtc_video_engine.h
+++ b/media/engine/webrtc_video_engine.h
@@ -478,11 +478,6 @@
   const absl::optional<VideoCodecSettings>& send_codec() const {
     return send_codec_;
   }
-  // Disabled function from interface
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
   webrtc::TaskQueueBase* const worker_thread_;
   webrtc::ScopedTaskSafety task_safety_;
   RTC_NO_UNIQUE_ADDRESS webrtc::SequenceChecker network_thread_checker_{
@@ -834,12 +829,6 @@
     RTC_DCHECK_RUN_ON(&thread_checker_);
     return unsignaled_stream_params_;
   }
-
-  // Disabled function from API
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
   // Variables.
   webrtc::TaskQueueBase* const worker_thread_;
   webrtc::ScopedTaskSafety task_safety_;
diff --git a/media/engine/webrtc_voice_engine.h b/media/engine/webrtc_voice_engine.h
index 327beed..0f7313e 100644
--- a/media/engine/webrtc_voice_engine.h
+++ b/media/engine/webrtc_voice_engine.h
@@ -302,10 +302,6 @@
       absl::AnyInvocable<void()> callback) override {
     send_codec_changed_callback_ = std::move(callback);
   }
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
 
  private:
   bool SetOptions(const AudioOptions& options);
@@ -458,11 +454,6 @@
   void SetReceiveNackEnabled(bool enabled) override;
   void SetReceiveNonSenderRttEnabled(bool enabled) override;
 
-  MediaChannel* ImplForTesting() override {
-    RTC_CHECK_NOTREACHED();
-    return nullptr;
-  }
-
  private:
   bool SetOptions(const AudioOptions& options);
   bool SetRecvCodecs(const std::vector<AudioCodec>& codecs);