AudioDecoder: New method SampleRateHz, + implementations for our codecs

webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc

Index: webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc
diff --git a/webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc b/webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc
index 7676e90d9e4f9420f101aeb69b96daabe475680b..379293b748b043985488e180934c2dd5c9baf060 100644
--- a/webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc
+++ b/webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.cc
@@ -35,7 +35,7 @@ int AudioDecoderG722::DecodeInternal(const uint8_t* encoded,
                                      int sample_rate_hz,
                                      int16_t* decoded,
                                      SpeechType* speech_type) {
-  RTC_DCHECK_EQ(sample_rate_hz, 16000);
+  RTC_DCHECK_EQ(SampleRateHz(), sample_rate_hz);
   int16_t temp_type = 1;  // Default is speech.
   size_t ret =
       WebRtcG722_Decode(dec_state_, encoded, encoded_len, decoded, &temp_type);
@@ -53,6 +53,10 @@ int AudioDecoderG722::PacketDuration(const uint8_t* encoded,
   return static_cast<int>(2 * encoded_len / Channels());
 }
 
+int AudioDecoderG722::SampleRateHz() const {
+  return 16000;
+}
+
 size_t AudioDecoderG722::Channels() const {
   return 1;
 }
@@ -74,7 +78,7 @@ int AudioDecoderG722Stereo::DecodeInternal(const uint8_t* encoded,
                                            int sample_rate_hz,
                                            int16_t* decoded,
                                            SpeechType* speech_type) {
-  RTC_DCHECK_EQ(sample_rate_hz, 16000);
+  RTC_DCHECK_EQ(SampleRateHz(), sample_rate_hz);
   int16_t temp_type = 1;  // Default is speech.
   // De-interleave the bit-stream into two separate payloads.
   uint8_t* encoded_deinterleaved = new uint8_t[encoded_len];
@@ -100,6 +104,10 @@ int AudioDecoderG722Stereo::DecodeInternal(const uint8_t* encoded,
   return static_cast<int>(ret);
 }
 
+int AudioDecoderG722Stereo::SampleRateHz() const {
+  return 16000;
+}
+
 size_t AudioDecoderG722Stereo::Channels() const {
   return 2;
 }