WebRtcVoiceEngine: Use AudioDecoderFactory to generate recv codecs.

webrtc/media/engine/payload_type_mapper.h

Index: webrtc/media/engine/payload_type_mapper.h
diff --git a/webrtc/media/engine/payload_type_mapper.h b/webrtc/media/engine/payload_type_mapper.h
index d1f8f35949adbf8fe68189264b305b0405958c83..a79fb4756c644f9274fe2fe34b0bb36f74a94f78 100644
--- a/webrtc/media/engine/payload_type_mapper.h
+++ b/webrtc/media/engine/payload_type_mapper.h
@@ -11,6 +11,44 @@
 #ifndef WEBRTC_MEDIA_ENGINE_PAYLOAD_TYPE_MAPPER_H_
 #define WEBRTC_MEDIA_ENGINE_PAYLOAD_TYPE_MAPPER_H_
 
-// This file intentionally left blank for build purposes.
+#include <map>
+#include <set>
 
+#include "webrtc/base/optional.h"
+#include "webrtc/media/base/codec.h"
+#include "webrtc/modules/audio_coding/codecs/audio_format.h"
+
+namespace cricket {
+
+class PayloadTypeMapper {
+ public:
+  PayloadTypeMapper();
+  ~PayloadTypeMapper();
+
+  // Finds the current payload type for |format| or assigns a new one, if no
+  // current mapping exists. Will return an empty value if it was unable to
+  // create a mapping, i.e. if all dynamic payload type ids have been used up.
+  rtc::Optional<int> GetMappingFor(const webrtc::SdpAudioFormat& format);
+
+  // Finds the current payload type for |format|, if any. Returns an empty value
+  // if no payload type mapping exists for the format.
+  rtc::Optional<int> FindMappingFor(const webrtc::SdpAudioFormat& format) const;
+
+  // Like GetMappingFor, but fills in an AudioCodec structure with the necessary
+  // information instead.
+  rtc::Optional<AudioCodec> ToAudioCodec(const webrtc::SdpAudioFormat& format);
+
+ private:
+  struct SdpAudioFormatOrdering {
+    bool operator()(const webrtc::SdpAudioFormat& a,
+                    const webrtc::SdpAudioFormat& b) const;
+  };
+
+  int next_unused_payload_type_;
+  int max_payload_type_;
+  std::map<webrtc::SdpAudioFormat, int, SdpAudioFormatOrdering> mappings_;
+  std::set<int> used_payload_types_;
+};
+
+}  // namespace cricket
 #endif  // WEBRTC_MEDIA_ENGINE_PAYLOAD_TYPE_MAPPER_H_