Use 'pssh' data to determine key_id properly

media/cdm/cenc_utils.cc

 // Copyright 2015 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 "media/cdm/cenc_utils.h"
 
 #include "media/base/bit_reader.h"
 
 namespace media {
 
@@ skipping 152 matching lines @@
         key.push_back(ReadBits(&reader, 8));
       }
       result.push_back(key);
       --count;
     }
 
     // Don't bother checking DataSize and Data.
   }
 
   key_ids->swap(result);
-
-  // TODO(jrummell): This should return true only if there was at least one
-  // key ID present. However, numerous test files don't contain the 'pssh' box
-  // for Common Format, so no keys are found. http://crbug.com/460308
-  return true;
+  return key_ids->size() > 0;
 }
 
 }  // namespace media