Use std::string references instead of copying contents.

talk/session/media/mediasession.cc

 /*
  * libjingle
  * Copyright 2004 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 511 matching lines @@
 // |bundle_group| should be updated to use the ufrag and pwd of the first
 // content within the |bundle_group|.
 static bool UpdateTransportInfoForBundle(const ContentGroup& bundle_group,
                                          SessionDescription* sdesc) {
   // The bundle should not be empty.
   if (!sdesc || !bundle_group.FirstContentName()) {
     return false;
   }
 
   // We should definitely have a transport for the first content.
-  std::string selected_content_name = *bundle_group.FirstContentName();
+  const std::string& selected_content_name = *bundle_group.FirstContentName();
   const TransportInfo* selected_transport_info =
       sdesc->GetTransportInfoByName(selected_content_name);
   if (!selected_transport_info) {
     return false;
   }
 
   // Set the other contents to use the same ICE credentials.
-  const std::string selected_ufrag =
+  const std::string& selected_ufrag =
       selected_transport_info->description.ice_ufrag;
-  const std::string selected_pwd =
+  const std::string& selected_pwd =
       selected_transport_info->description.ice_pwd;
   for (TransportInfos::iterator it =
            sdesc->transport_infos().begin();
        it != sdesc->transport_infos().end(); ++it) {
     if (bundle_group.HasContentName(it->content_name) &&
         it->content_name != selected_content_name) {
       it->description.ice_ufrag = selected_ufrag;
       it->description.ice_pwd = selected_pwd;
     }
   }
@@ skipping 1394 matching lines @@
   } else if (channel_name == GICE_CHANNEL_NAME_DATA_RTP ||
              channel_name == GICE_CHANNEL_NAME_DATA_RTCP) {
     *media_type = MEDIA_TYPE_DATA;
     return true;
   }
 
   return false;
 }
 
 }  // namespace cricket