Move function for classifying a string as a mime type into MimeUtil

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 ba3e25dd389d8ceca03a52b2a723dc1e9ee067c1..ff70f4af1f74ffe243b66b1e85a167ef3458c71e 100644
--- a/net/base/mime_util.h
+++ b/net/base/mime_util.h
@@ -58,6 +58,11 @@ NET_EXPORT bool IsSupportedMimeType(const std::string& mime_type);
 NET_EXPORT bool MatchesMimeType(const std::string& mime_type_pattern,
                                 const std::string& mime_type);
 
+// Returns true if the |type_string| is a correctly-formed mime type specifier.
+// Allows strings of the form x/y[;params], where "x" is a legal mime type name.
+// Also allows wildcard types -- "x/*", "*/*", and "*".
+NET_EXPORT bool IsMimeType(const std::string& type_string);
+
 // Returns true if and only if all codecs are supported, false otherwise.
 NET_EXPORT bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs);