Don't forget to support G722 stereo decoding

webrtc/api/audio_codecs/g722/audio_decoder_g722.h

Index: webrtc/api/audio_codecs/g722/audio_decoder_g722.h
diff --git a/webrtc/api/audio_codecs/g722/audio_decoder_g722.h b/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
index 32a46d7348e92e783cea47097e0c18b7671e6172..ef536628bbe570486aa1b3c2793af40ef2f05f7d 100644
--- a/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
+++ b/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
@@ -25,7 +25,10 @@ namespace webrtc {
 //
 // NOTE: This struct is still under development and may change without notice.
 struct AudioDecoderG722 {
-  struct Config {};  // Empty---no config values needed!
+  struct Config {
+    bool IsOk() const { return num_channels == 1 || num_channels == 2; }
+    int num_channels;
+  };
   static rtc::Optional<Config> SdpToConfig(const SdpAudioFormat& audio_format);
   static void AppendSupportedDecoders(std::vector<AudioCodecSpec>* specs);
   static std::unique_ptr<AudioDecoder> MakeAudioDecoder(Config config);