ppapi: Support up to 32 subsamples in PP_EncryptedBlockInfo.

ppapi/api/private/pp_content_decryptor.idl

Index: ppapi/api/private/pp_content_decryptor.idl
diff --git a/ppapi/api/private/pp_content_decryptor.idl b/ppapi/api/private/pp_content_decryptor.idl
index a952e0b0846c89615dd5c449cf2784f2ed233dca..690c8c76700c17a7f2240b99c35835134b682e71 100644
--- a/ppapi/api/private/pp_content_decryptor.idl
+++ b/ppapi/api/private/pp_content_decryptor.idl
@@ -81,7 +81,7 @@ struct PP_DecryptSubsampleDescription {
  * 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.
@@ -113,8 +113,13 @@ struct PP_EncryptedBlockInfo {
 
   /**
    * 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;
 };