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;
@@ skipping 11 matching lines @@
   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.
+   *
+   * TODO(xhwang): 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;

[xhwang, 2015/10/19 20:47:26]

This is the real change in this CL :)

[bbudge, 2015/10/20 17:38:15]

Usually we version the struct. See ppb_video_decoder.idl and pp_codec.idl for
examples.

[xhwang, 2015/10/20 18:30:54]

(Also for your question below.)

We always ship the plugin together (in-sync) with Chrome, so there are no
compatibility issues. In that case, I guess we don't need to keep the old
structure and use versioning here?

   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;
 };