Make CodecType conversion functions non-optional.

webrtc/common_types.h

Index: webrtc/common_types.h
diff --git a/webrtc/common_types.h b/webrtc/common_types.h
index dc62b632a1c89782d9d51e684285f5ab41877703..ecfa15d2c940a9e4828d29997c169afdd87ef8c4 100644
--- a/webrtc/common_types.h
+++ b/webrtc/common_types.h
@@ -537,6 +537,10 @@ enum VideoCodecType {
 };
 
 // Translates from name of codec to codec type and vice versa.
+const char* CodecTypeToPayloadString(VideoCodecType type);
+VideoCodecType PayloadStringToCodecType(const std::string& name);
+// TODO(kthelgason): Remove these methods once upstream projects
+// have been updated.
 rtc::Optional<const char*> CodecTypeToPayloadName(VideoCodecType type);
 rtc::Optional<VideoCodecType> PayloadNameToCodecType(const std::string& name);