Cache the subtype of each DecoderInfo to make the Is* checks quicker.

webrtc/modules/audio_coding/neteq/decoder_database.cc

Index: webrtc/modules/audio_coding/neteq/decoder_database.cc
diff --git a/webrtc/modules/audio_coding/neteq/decoder_database.cc b/webrtc/modules/audio_coding/neteq/decoder_database.cc
index 27bc6d56970c9835300fc1cb398c387a6f03b220..9526c47a83b3206e439891171e14c21c6d1bb2db 100644
--- a/webrtc/modules/audio_coding/neteq/decoder_database.cc
+++ b/webrtc/modules/audio_coding/neteq/decoder_database.cc
@@ -31,20 +31,23 @@ DecoderDatabase::DecoderInfo::DecoderInfo(const SdpAudioFormat& audio_format,
     : audio_format_(audio_format),
       factory_(factory),
       external_decoder_(nullptr),
-      cng_decoder_(CngDecoder::Create(audio_format)) {}
+      cng_decoder_(CngDecoder::Create(audio_format)),
+      subtype_(SubtypeFromFormat(audio_format)) {}
 
 DecoderDatabase::DecoderInfo::DecoderInfo(NetEqDecoder ct,
                                           AudioDecoderFactory* factory)
     : audio_format_(*acm2::RentACodec::NetEqDecoderToSdpAudioFormat(ct)),
       factory_(factory),
       external_decoder_(nullptr),
-      cng_decoder_(CngDecoder::Create(audio_format_)) {}
+      cng_decoder_(CngDecoder::Create(audio_format_)),
+      subtype_(SubtypeFromFormat(audio_format_)) {}
 
 DecoderDatabase::DecoderInfo::DecoderInfo(const SdpAudioFormat& audio_format,
                                           AudioDecoder* ext_dec)
     : audio_format_(audio_format),
       factory_(nullptr),
-      external_decoder_(ext_dec) {
+      external_decoder_(ext_dec),
+      subtype_(Subtype::kNormal) {
   RTC_CHECK(ext_dec);
 }
 
@@ -72,16 +75,16 @@ AudioDecoder* DecoderDatabase::DecoderInfo::GetDecoder() const {
 }
 
 bool DecoderDatabase::DecoderInfo::IsComfortNoise() const {
-  RTC_DCHECK_EQ(!!cng_decoder_, IsType("CN"));
-  return !!cng_decoder_;
+  RTC_DCHECK_EQ(!!cng_decoder_, subtype_ == Subtype::kComfortNoise);
+  return subtype_ == Subtype::kComfortNoise;
 }
 
 bool DecoderDatabase::DecoderInfo::IsDtmf() const {
-  return IsType("telephone-event");
+  return subtype_ == Subtype::kDtmf;
 }
 
 bool DecoderDatabase::DecoderInfo::IsRed() const {
-  return IsType("red");
+  return subtype_ == Subtype::kRed;
 }
 
 bool DecoderDatabase::DecoderInfo::IsType(const char* name) const {
@@ -101,6 +104,19 @@ DecoderDatabase::DecoderInfo::CngDecoder::Create(const SdpAudioFormat& format) {
   }
 }
 
+DecoderDatabase::DecoderInfo::Subtype
+DecoderDatabase::DecoderInfo::SubtypeFromFormat(const SdpAudioFormat& format) {
+  if (STR_CASE_CMP(format.name.c_str(), "CN") == 0) {
+    return Subtype::kComfortNoise;
+  } else if (STR_CASE_CMP(format.name.c_str(), "telephone-event") == 0) {
+    return Subtype::kDtmf;
+  } else if (STR_CASE_CMP(format.name.c_str(), "red") == 0) {
+    return Subtype::kRed;
+  }
+
+  return Subtype::kNormal;
+}
+
 bool DecoderDatabase::Empty() const { return decoders_.empty(); }
 
 int DecoderDatabase::Size() const { return static_cast<int>(decoders_.size()); }