KeySystems: IsSupportedContainerAndCodecs() ignores empty codec.

In IsTypeSupported() call, when the codec string in the mime type contains extra
commas, e.g. ",vorbis", an empty codec will be passed into
IsSupportedContainerAndCodecs. In this case, we should ignore that codec instead
of assuming it's not empty.

BUG=362769
TEST=Layout test crash is fixed.
R=ddorwin@chromium.org

Review URL: https://codereview.chromium.org/254913002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266335 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/media/crypto/key_systems.cc

@@ -281,7 +281,8 @@ bool KeySystems::IsSupportedContainerAndCodecs(
 
   for (size_t i = 0; i < codecs.size(); ++i) {
     const std::string& codec = codecs[i];
-    DCHECK(!codec.empty());
+    if (codec.empty())
+      continue;
     CodecMaskMap::const_iterator codec_iter = codec_masks_.find(codec);
     if (codec_iter == codec_masks_.end())  // Unrecognized codec.
       return false;