Opus extension to mimetype map so files with .opus play instead of download.

net/base/mime_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <string>
 
 #include "net/base/mime_util.h"
@@ skipping 111 matching lines @@
   { "text/css", "css" },
   { "text/xml", "xml" },
   { "image/gif", "gif" },
   { "image/jpeg", "jpeg,jpg" },
   { "image/webp", "webp" },
   { "image/png", "png" },
   { "video/mp4", "mp4,m4v" },
   { "audio/x-m4a", "m4a" },
   { "audio/mp3", "mp3" },
   { "video/ogg", "ogv,ogm" },
-  { "audio/ogg", "ogg,oga" },
+  { "audio/ogg", "ogg,oga,opus" },
   { "video/webm", "webm" },
   { "audio/webm", "webm" },
   { "audio/wav", "wav" },
   { "application/xhtml+xml", "xhtml,xht" },
   { "application/x-chrome-extension", "crx" },
   { "multipart/related", "mhtml,mht" }
 };
 
 static const MimeInfo secondary_mappings[] = {
   { "application/octet-stream", "exe,com,bin" },
@@ skipping 833 matching lines @@
   return CERTIFICATE_MIME_TYPE_UNKNOWN;
 }
 
 bool IsSupportedCertificateMimeType(const std::string& mime_type) {
   CertificateMimeType file_type =
       GetCertificateMimeTypeForMimeType(mime_type);
   return file_type != CERTIFICATE_MIME_TYPE_UNKNOWN;
 }
 
 }  // namespace net