diff -up chromium-52.0.2716.0/media/base/mime_util_internal.cc.matroska-avi chromium-52.0.2716.0/media/base/mime_util_internal.cc
--- chromium-52.0.2716.0/media/base/mime_util_internal.cc.matroska-avi	2016-04-27 00:02:52.000000000 +0200
+++ chromium-52.0.2716.0/media/base/mime_util_internal.cc	2016-04-27 08:42:25.933047659 +0200
@@ -76,7 +76,11 @@ static const CodecIDMappings kUnambiguou
     {"opus", MimeUtil::OPUS},
     {"vp8", MimeUtil::VP8},
     {"vp8.0", MimeUtil::VP8},
-    {"theora", MimeUtil::THEORA}};
+    {"theora", MimeUtil::THEORA},
+    {"dts", MimeUtil::DTS},
+    {"mp2", MimeUtil::MP2},
+    {"mp4v.20.9", MimeUtil::MPEG4_SP},
+    {"mp4v.20.240", MimeUtil::MPEG4_ASP}};
 
 // List of codec IDs that are ambiguous and don't provide
 // enough information to determine the codec and profile.
@@ -325,6 +329,31 @@ void MimeUtil::AddSupportedMediaFormats(
 #endif  // !defined(OS_ANDROID)
   CodecSet ogg_codecs(ogg_audio_codecs);
   ogg_codecs.insert(ogg_video_codecs.begin(), ogg_video_codecs.end());
+  
+  CodecSet matroska_audio_codecs;
+  matroska_audio_codecs.insert(OPUS);
+  matroska_audio_codecs.insert(VORBIS);
+  matroska_audio_codecs.insert(AC3);
+  matroska_audio_codecs.insert(EAC3);
+  matroska_audio_codecs.insert(DTS);
+  matroska_audio_codecs.insert(MP3);
+  matroska_audio_codecs.insert(MP2);
+  matroska_audio_codecs.insert(MPEG2_AAC);
+  matroska_audio_codecs.insert(MPEG4_AAC);
+  matroska_audio_codecs.insert(PCM);
+  
+  CodecSet matroska_video_codecs;
+  matroska_video_codecs.insert(THEORA);
+  matroska_video_codecs.insert(VP8);
+  matroska_video_codecs.insert(VP9);
+  matroska_video_codecs.insert(H264);
+  matroska_video_codecs.insert(MPEG4_SP);
+  matroska_video_codecs.insert(MPEG4_ASP);
+#if BUILDFLAG(ENABLE_HEVC_DEMUXING)
+  matroska_video_codecs.insert(HEVC);
+#endif  // BUILDFLAG(ENABLE_HEVC_DEMUXING)
+  CodecSet matroska_codecs(matroska_audio_codecs);
+  matroska_codecs.insert(matroska_video_codecs.begin(), matroska_video_codecs.end());
 
   CodecSet webm_audio_codecs;
   webm_audio_codecs.insert(OPUS);
@@ -380,6 +409,9 @@ void MimeUtil::AddSupportedMediaFormats(
   // TODO(ddorwin): Should the application type support Opus?
   AddContainerWithCodecs("application/ogg", ogg_codecs, false);
 
+  AddContainerWithCodecs("audio/x-matroska", matroska_audio_codecs, false);
+  AddContainerWithCodecs("video/x-matroska", matroska_codecs, false);
+
 #if defined(USE_PROPRIETARY_CODECS)
   AddContainerWithCodecs("audio/mpeg", mp3_codecs, true);  // Allow "mp3".
   AddContainerWithCodecs("audio/mp3", implicit_codec, true);
@@ -733,6 +765,9 @@ bool MimeUtil::IsCodecProprietary(Codec
     case MPEG4_AAC:
     case H264:
     case HEVC:
+    case DTS:
+    case MPEG4_SP:
+    case MPEG4_ASP:
       return true;
 
     case PCM:
diff -up chromium-52.0.2716.0/media/base/mime_util_internal.h.matroska-avi chromium-52.0.2716.0/media/base/mime_util_internal.h
--- chromium-52.0.2716.0/media/base/mime_util_internal.h.matroska-avi	2016-04-27 00:02:52.000000000 +0200
+++ chromium-52.0.2716.0/media/base/mime_util_internal.h	2016-04-27 08:14:04.560330601 +0200
@@ -39,7 +39,11 @@ class MEDIA_EXPORT MimeUtil {
     VP8,
     VP9,
     THEORA,
-    LAST_CODEC = THEORA
+    DTS,
+    MP2,
+    MPEG4_SP,
+    MPEG4_ASP,
+    LAST_CODEC = MPEG4_ASP
   };
 
   // Platform configuration structure.  Controls which codecs are supported at
diff -up chromium-52.0.2716.0/net/base/mime_util.cc.matroska-avi chromium-52.0.2716.0/net/base/mime_util.cc
--- chromium-52.0.2716.0/net/base/mime_util.cc.matroska-avi	2016-04-27 00:02:52.000000000 +0200
+++ chromium-52.0.2716.0/net/base/mime_util.cc	2016-04-27 08:14:04.561330581 +0200
@@ -78,6 +78,9 @@ static const MimeInfo kPrimaryMappings[]
     {"audio/webm", "webm"},
     {"audio/wav", "wav"},
     {"audio/flac", "flac"},
+    {"video/x-matroska", "mkv"},
+    {"audio/x-matroska", "mkv"},
+    {"video/x-msvideo", "avi"},
     {"application/xhtml+xml", "xhtml,xht,xhtm"},
     {"application/x-chrome-extension", "crx"},
     {"multipart/related", "mhtml,mht"}};
@@ -425,6 +428,7 @@ static const char* const kStandardAudioT
   "audio/vorbis",
   "audio/wav",
   "audio/webm",
+  "audio/x-matroska",
   "audio/x-m4a",
   "audio/x-ms-wma",
   "audio/vnd.rn-realaudio",
@@ -442,6 +446,7 @@ static const char* const kStandardVideoT
   "video/webm",
   "video/x-dv",
   "video/x-m4v",
+  "video/x-matroska",
   "video/x-mpeg",
   "video/x-ms-asf",
   "video/x-ms-wmv"