Have media gallery (through native media file util) use MIME sniffer

net/base/mime_sniffer.h

Index: net/base/mime_sniffer.h
diff --git a/net/base/mime_sniffer.h b/net/base/mime_sniffer.h
index 9cdb2d709c76f185c1a096d3f3e4ddeccd96f44a..2a64b8526c11749c8044c06848baa60db5400097 100644
--- a/net/base/mime_sniffer.h
+++ b/net/base/mime_sniffer.h
@@ -41,6 +41,19 @@ NET_EXPORT bool SniffMimeType(const char* content, size_t content_size,
                               const GURL& url, const std::string& type_hint,
                               std::string* result);
 
+// Guess a MIME type from the first few bytes of content only.
+// Uses a bigger set of media file searches than |SniffMimeType()|.
+// If finds a match, fills in |result| and returns true,
+// otherwise returns false.
+//
+// @param content A buffer containing the bytes to sniff.
+// @param content_size The number of bytes in the |content| buffer.
+// @param result Address at which to place the sniffed mime type.
+// @return Returns true if we have enough content to guess the mime type.
+NET_EXPORT bool IdentifyExtraMimeType(const char* content,
+                                      size_t content_size,
+                                      std::string* result);
+
 }  // namespace net
 
 #endif  // NET_BASE_MIME_SNIFFER_H__