Added allow_codec_switching parameter to RTCConfig.

Bug: webrtc:10795
Change-Id: I5507f1d801e262223bd18198c685b5fffa644b0b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157891
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29612}
diff --git a/media/base/media_channel.h b/media/base/media_channel.h
index 582d29c..c49f2ec 100644
--- a/media/base/media_channel.h
+++ b/media/base/media_channel.h
@@ -243,6 +243,9 @@
       uint32_t ssrc,
       rtc::scoped_refptr<webrtc::FrameDecryptorInterface> frame_decryptor);
 
+  // Enable network condition based codec switching.
+  virtual void SetVideoCodecSwitchingEnabled(bool enabled);
+
   // Base method to send packet using NetworkInterface.
   bool SendPacket(rtc::CopyOnWriteBuffer* packet,
                   const rtc::PacketOptions& options) {