Have GetKeyIds() return the key IDs from the first matching 'pssh' box

media/cdm/cenc_utils.h

 // 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.
 
 #ifndef MEDIA_CDM_CENC_UTILS_H_
 #define MEDIA_CDM_CENC_UTILS_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "media/base/media_export.h"
 #include "media/cdm/json_web_key.h"
 
 namespace media {
 
 // Validate that |input| is a set of concatenated 'pssh' boxes and the sizes
 // match. Returns true if |input| looks valid, false otherwise.
 MEDIA_EXPORT bool ValidatePsshInput(const std::vector<uint8_t>& input);
 
-// Gets the Key Ids from a 'pssh' box for the Common SystemID among one or
-// more concatenated 'pssh' boxes. If |input| looks valid, then true is
-// returned and |key_ids| is updated to contain the values found. Otherwise
-// return false.
-MEDIA_EXPORT bool GetKeyIdsForCommonSystemId(const std::vector<uint8_t>& input,
-                                             KeyIdList* key_ids);
+// Gets the Key Ids from the first 'pssh' box for the Common System ID among one
+// or more concatenated 'pssh' boxes. Returns true if a matching box is found
+// and it contains 1 or more key IDs. Returns false otherwise.
+// Notes:
+// 1. If multiple PSSH boxes are found, the "KIDs" of the first matching 'pssh'
+//    box will be set in |key_ids|.
+// 2. Only PSSH boxes are allowed in |input|. Any other boxes in |pssh_boxes|
+//    will result in false being returned.
+MEDIA_EXPORT bool GetKeyIdsForCommonSystemId(
+    const std::vector<uint8_t>& pssh_boxes,
+    KeyIdList* key_ids);
 
-// Gets the data field from the first 'pssh' box containing |system_id| UUID.
+// Gets the data field from the first 'pssh' box containing |system_id|.
 // Returns true if such a box is found and successfully parsed. Returns false
 // otherwise.
 // Notes:
 // 1. If multiple PSSH boxes are found, the "Data" of the first matching 'pssh'
 //    box will be set in |pssh_data|.
-// 2. Only PSSH boxes are allowed in |input|.
+// 2. Only PSSH boxes are allowed in |input|. Any other boxes in |pssh_boxes|
+//    will result in false being returned.
 MEDIA_EXPORT bool GetPsshData(const std::vector<uint8_t>& input,
                               const std::vector<uint8_t>& system_id,
                               std::vector<uint8_t>* pssh_data);
 
 }  // namespace media
 
 #endif  // MEDIA_CDM_CENC_UTILS_H_