Add MimeUtil::Parse{Audio|Video}CodecString

media/base/video_codecs.cc

Index: media/base/video_codecs.cc
diff --git a/media/base/video_codecs.cc b/media/base/video_codecs.cc
index 4d1cdc45840e7a0fc137dd9b9a1607e8d7408a2c..6edf1633c51a7b1333c461bcda7015751aedcb82 100644
--- a/media/base/video_codecs.cc
+++ b/media/base/video_codecs.cc
@@ -237,9 +237,10 @@ bool ParseLegacyVp9CodecID(const std::string& codec_id,
                            VideoCodecProfile* profile,
                            uint8_t* level_idc) {
   if (codec_id == "vp9" || codec_id == "vp9.0") {
-    // Profile is not included in the codec string. Assuming profile 0 to be
-    // backward compatible.
-    *profile = VP9PROFILE_PROFILE0;
+    // Profile is not included in the codec string. Consumers of parsed codec
+    // should handle by rejecting ambiguous string or resolving to a default
+    // profile.
+    *profile = VIDEO_CODEC_PROFILE_UNKNOWN;
     // Use 0 to indicate unknown level.
     *level_idc = 0;
     return true;