WebRtcVoiceEngine: Use AudioDecoderFactory to generate recv codecs.

webrtc/modules/audio_coding/codecs/audio_format.cc

Index: webrtc/modules/audio_coding/codecs/audio_format.cc
diff --git a/webrtc/modules/audio_coding/codecs/audio_format.cc b/webrtc/modules/audio_coding/codecs/audio_format.cc
index bb69cbdb2f73be7f36f7983a0a4b7ae662cc03d1..22c8520ca8e1aa4762eeff3e75fba74b17994e56 100644
--- a/webrtc/modules/audio_coding/codecs/audio_format.cc
+++ b/webrtc/modules/audio_coding/codecs/audio_format.cc
@@ -10,6 +10,8 @@
 
 #include "webrtc/modules/audio_coding/codecs/audio_format.h"
 
+#include "webrtc/common_types.h"
+
 namespace webrtc {
 
 SdpAudioFormat::SdpAudioFormat() = default;
@@ -34,6 +36,19 @@ SdpAudioFormat::~SdpAudioFormat() = default;
 SdpAudioFormat& SdpAudioFormat::operator=(const SdpAudioFormat&) = default;
 SdpAudioFormat& SdpAudioFormat::operator=(SdpAudioFormat&&) = default;
 
+bool SdpAudioFormat::operator<(const SdpAudioFormat& b) const {
+  if (clockrate_hz == b.clockrate_hz) {
+    if (num_channels == b.num_channels) {
+      int name_cmp = STR_CASE_CMP(name.c_str(), b.name.c_str());
+      if (name_cmp == 0)
+        return parameters < b.parameters;
+      return name_cmp < 0;
+    }
+    return num_channels < b.num_channels;
+  }
+  return clockrate_hz < b.clockrate_hz;
+}
+
 void swap(SdpAudioFormat& a, SdpAudioFormat& b) {
   using std::swap;
   swap(a.name, b.name);