Fix canPlayType() support for non-RFC compliant mp3 mimetype.

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 "base/containers/hash_tables.h"
@@ skipping 455 matching lines @@
 };
 
 static const MediaFormatStrict format_codec_mappings[] = {
   { "video/webm", "opus,vorbis,vp8,vp8.0,vp9,vp9.0" },
   { "audio/webm", "opus,vorbis" },
   { "audio/wav", "1" },
   { "audio/x-wav", "1" },
   { "video/ogg", "opus,theora,vorbis" },
   { "audio/ogg", "opus,vorbis" },
   { "application/ogg", "opus,theora,vorbis" },
-  { "audio/mpeg", "" },
+  { "audio/mpeg", ",mp3" }, // Note: Empty string codec ID indicates

[DaleCurtis, 2014/07/17 18:41:55]

I'm not convinced it's a good idea, but I wonder if a magic word like ::EMPTY::
would be better in this case.  It wasn't immediately clear that you meant the
prefixed comma was providing the empty string. 

[acolwell GONE FROM CHROMIUM, 2014/07/17 18:57:00]

I agree that this isn't awesome, but I fear some sort of "special" string might
lead to other problems if someone is crafty about what they pass to
canPlayType(). I've updated the comment to clarify what is going on with the
comma at the beginning so hopefully that helps.

+                            // a missing codecs= parameter is also valid.
+                            // The presense of 'mp3' is not RFC compliant,
+                            // but is common in the wild so it is a defacto
+                            // standard.
   { "audio/mp3", "" },
   { "audio/x-mp3", "" }
 };
 
 // Following is the list of RFC 6381 compliant codecs:
 //   mp4a.6B     - MPEG-1 audio
 //   mp4a.69     - MPEG-2 extension to MPEG-1
 //   mp4a.67     - MPEG-2 AAC
 //   mp4a.40.2   - MPEG-4 AAC
 //   mp4a.40.5   - MPEG-4 HE-AAC
@@ skipping 25 matching lines @@
 MimeUtil::MimeUtil() {
   InitializeMimeTypeMaps();
 }
 
 // static
 bool MimeUtil::AreSupportedCodecs(const MimeMappings& supported_codecs,
                                   const std::vector<std::string>& codecs) {
   if (supported_codecs.empty())
     return codecs.empty();
 
+  // If no codecs are specified in the mimetype, check to see if a missing
+  // codecs parameter is allowed.
+  if (codecs.empty())
+    return supported_codecs.find("") != supported_codecs.end();

[Ryan Sleevi, 2014/07/17 18:38:08]

.find(std::string())

[acolwell GONE FROM CHROMIUM, 2014/07/17 18:57:00]

Done.

+
   for (size_t i = 0; i < codecs.size(); ++i) {
-    if (supported_codecs.find(codecs[i]) == supported_codecs.end())
+    if (supported_codecs.find(codecs[i]) == supported_codecs.end() ||
+        codecs[i].empty())

[Ryan Sleevi, 2014/07/17 18:38:08]

Do the .empty() check before the .find(), and avoid the lookup.

[acolwell GONE FROM CHROMIUM, 2014/07/17 18:57:00]

Done.

       return false;
   }
-  return !codecs.empty();
+
+  return true;
 }
 
 // Checks all the codecs present in the |codecs| against the entries in
 // |supported_codecs|. Returns true only if |codecs| is non-empty and all the
 // codecs match |supported_codecs| expressions.
 bool MimeUtil::AreSupportedCodecsWithProfile(
     const MimeExpressionMappings& supported_codecs,
     const std::vector<std::string>& codecs) {
   DCHECK(!supported_codecs.empty());
   for (size_t i = 0; i < codecs.size(); ++i) {
@@ skipping 638 matching lines @@
   post_data->append("\r\n" + value + "\r\n");
 }
 
 void AddMultipartFinalDelimiterForUpload(const std::string& mime_boundary,
                                          std::string* post_data) {
   DCHECK(post_data);
   post_data->append("--" + mime_boundary + "--\r\n");
 }
 
 }  // namespace net