ppapi: Support up to 32 subsamples in PP_EncryptedBlockInfo.

ppapi/api/private/pp_content_decryptor.idl

 /* Copyright (c) 2012 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.
  */
 
 /**
  * The <code>PP_DecryptTrackingInfo</code> struct contains necessary information
  * that can be used to associate the decrypted block with a decrypt request
  * and/or an input block.
  */
@@ skipping 63 matching lines @@
   /**
    * Size in bytes of encrypted data in a subsample entry.
    */
   uint32_t cipher_bytes;
 };
 
 /**
  * The <code>PP_EncryptedBlockInfo</code> struct contains all the information
  * needed to decrypt an encrypted block.
  */
-[assert_size(240)]
+[assert_size(368)]
 struct PP_EncryptedBlockInfo {
   /**
    * Information needed by the client to track the block to be decrypted.
    */
   PP_DecryptTrackingInfo tracking_info;
 
   /**
    * Size in bytes of data to be decrypted (data_offset included).
    */
   uint32_t data_size;
 
   /**
    * Key ID of the block to be decrypted.
    *
-   * TODO(xhwang): For WebM the key ID can be as large as 2048 bytes in theory.
-   * But it's not used in current implementations. If we really need to support
-   * it, we should move key ID out as a separate parameter, e.g.
-   * as a <code>PP_Var</code>, or make the whole
-   * <code>PP_EncryptedBlockInfo</code> as a <code>PP_Resource</code>.
+   * For WebM the key ID can be as large as 2048 bytes in theory. But it's not
+   * used in current implementations. If we really need to support it, we should
+   * move key ID out as a separate parameter, e.g. as a <code>PP_Var</code>, or
+   * make the whole <code>PP_EncryptedBlockInfo</code> as a
+   * <code>PP_Resource</code>.
    */
   uint8_t[64] key_id;
   uint32_t key_id_size;
 
   /**
    * Initialization vector of the block to be decrypted.
    */
   uint8_t[16] iv;
   uint32_t iv_size;
 
   /**
    * Subsample information of the block to be decrypted.
+   *
+   * We need to have a fixed size of |subsamples| here. Choose 32 because it is
+   * sufficient for almost all real life scenarios. Note that in theory the
+   * number of subsamples could be larger than 32. If that happens, playback
+   * will fail.
    */
-  PP_DecryptSubsampleDescription[16] subsamples;
+  PP_DecryptSubsampleDescription[32] subsamples;
   uint32_t num_subsamples;
 };
 
 /**
  * <code>PP_DecryptedFrameFormat</code> contains video frame formats.
  */
 [assert_size(4)]
 enum PP_DecryptedFrameFormat {
   PP_DECRYPTEDFRAMEFORMAT_UNKNOWN = 0,
   PP_DECRYPTEDFRAMEFORMAT_YV12 = 1,
@@ skipping 345 matching lines @@
   /**
    * Status of this key.
    */
   PP_CdmKeyStatus key_status;
 
   /**
    * Optional error code for keys that are not usable.
    */
   uint32_t system_code;
 };