Refactoring media mime type and supported codec checks

net/base/mime_util.h

Index: net/base/mime_util.h
diff --git a/net/base/mime_util.h b/net/base/mime_util.h
index 09a3c7e3c7ec4a976eae0340789a76357b801635..eedf041ce93256da882ae3d6f5891b9def8a738e 100644
--- a/net/base/mime_util.h
+++ b/net/base/mime_util.h
@@ -20,6 +20,7 @@
 #include <string>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/files/file_path.h"
 #include "net/base/net_export.h"
 
@@ -101,6 +102,19 @@ NET_EXPORT void ParseCodecString(const std::string& codecs,
                                  std::vector<std::string>* codecs_out,
                                  bool strip);
 
+// Returns true if the given |codec_id|, identified by a codec id string
+// described in RFC 6381, is supported. Returns false if the codec id is not
+// recognized or if that codec is not supported.
+NET_EXPORT bool IsCodecSupported(const std::string& codec_id);
+
+// The default implementation of IsCodecSupported, it can be overridden by
+// providing a custom callback via SetIsCodecSupportedCB.
+NET_EXPORT bool DefaultIsCodecSupported(const std::string& codec_id);
+
+// Provides a custom, platform-specific implementation of IsCodecSupported.
+typedef base::Callback<bool(const std::string&)> IsCodecSupportedCB;
+NET_EXPORT void SetIsCodecSupportedCB(IsCodecSupportedCB is_codec_supported_cb);

[Ryan Sleevi, 2015/04/21 13:23:29]

STYLE: Callbacks should *always* be passed as const-ref

DESIGN: Is the typedef actually necessary? It seems cleaner (e.g. avoiding
namespace polution) to avoid it.

[servolk, 2015/04/21 22:09:02]

Changed to const-ref. Re typedef - I've posted my reasoning in an earlier
comment, let me know which you prefer.

+
 // Check to see if a particular MIME type is in our list which only supports a
 // certain subset of codecs.
 NET_EXPORT bool IsStrictMediaMimeType(const std::string& mime_type);