diff -up chromium-64.0.3282.119/media/base/mime_util_internal.cc.mp3 chromium-64.0.3282.119/media/base/mime_util_internal.cc
--- chromium-64.0.3282.119/media/base/mime_util_internal.cc.mp3	2018-01-24 15:05:48.000000000 -0500
+++ chromium-64.0.3282.119/media/base/mime_util_internal.cc	2018-01-25 11:18:12.354147726 -0500
@@ -279,15 +279,19 @@ void MimeUtil::AddSupportedMediaFormats(
   CodecSet webm_codecs(webm_audio_codecs);
   webm_codecs.insert(webm_video_codecs.begin(), webm_video_codecs.end());
 
-#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   const CodecSet mp3_codecs{MP3};
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   const CodecSet aac{MPEG2_AAC, MPEG4_AAC};
+#else
+  const CodecSet aac{};
+#endif
+  CodecSet mp4_audio_codecs(aac);
+  mp4_audio_codecs.emplace(MP3);
 
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   CodecSet avc_and_aac(aac);
   avc_and_aac.emplace(H264);
 
-  CodecSet mp4_audio_codecs(aac);
-  mp4_audio_codecs.emplace(MP3);
   mp4_audio_codecs.emplace(FLAC);
 #if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
   mp4_audio_codecs.emplace(AC3);
@@ -329,10 +333,10 @@ void MimeUtil::AddSupportedMediaFormats(
   AddContainerWithCodecs("application/ogg", ogg_codecs, false);
   AddContainerWithCodecs("audio/flac", implicit_codec, false);
 
-#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   AddContainerWithCodecs("audio/mpeg", mp3_codecs, true);  // Allow "mp3".
   AddContainerWithCodecs("audio/mp3", implicit_codec, true);
   AddContainerWithCodecs("audio/x-mp3", implicit_codec, true);
+#if BUILDFLAG(USE_PROPRIETARY_CODECS)
   AddContainerWithCodecs("audio/aac", implicit_codec, true);  // AAC / ADTS.
   AddContainerWithCodecs("audio/mp4", mp4_audio_codecs, true);
   DCHECK(!mp4_video_codecs.empty());
@@ -970,7 +974,6 @@ bool MimeUtil::IsCodecProprietary(Codec
     case INVALID_CODEC:
     case AC3:
     case EAC3:
-    case MP3:
     case MPEG2_AAC:
     case MPEG4_AAC:
     case H264:
@@ -978,6 +981,7 @@ bool MimeUtil::IsCodecProprietary(Codec
     case DOLBY_VISION:
       return true;
 
+    case MP3:
     case PCM:
     case VORBIS:
     case OPUS: