Pass DecryptConfig parameters over IPC and use it in AVDA.

media/base/decoder_buffer.cc

Index: media/base/decoder_buffer.cc
diff --git a/media/base/decoder_buffer.cc b/media/base/decoder_buffer.cc
index a8624b1e8e705090aea221e23a2ee58154502580..ce02937864ea49f0ff942478ade0127ac4576e58 100644
--- a/media/base/decoder_buffer.cc
+++ b/media/base/decoder_buffer.cc
@@ -99,6 +99,10 @@ std::string DecoderBuffer::AsHumanReadableString() {
     << " encrypted: " << (decrypt_config_ != NULL)
     << " discard_padding (ms): (" << discard_padding_.first.InMilliseconds()
     << ", " << discard_padding_.second.InMilliseconds() << ")";
+
+  if (decrypt_config_)
+    s << " decrypt:" << (*decrypt_config_);
+
   return s.str();
 }