Drop the DCHECK for language size 3

Language tags can have subtags, such as "por-BR".  While the base tag
should be 3 characters, the entire tag can be longer.  Rather than
parse out the base tag and check that it is size 3 without the subtag,
we can just trust the ISO tag converter to do the right thing.

Change-Id: I2a186b5c8db0f373ee82ef68245ecc33cb068581

packager/app/stream_descriptor.cc

@@ -117,7 +117,6 @@ bool InsertStreamDescriptor(const std::string& descriptor_string,
           LOG(ERROR) << "Unknown/invalid language specified: " << iter->second;
           return false;
         }
-        DCHECK_EQ(3u, language.size());
         descriptor.language = language;
         break;
       }