Support encrypted audio stream in demuxer.

media/webm/webm_tracks_parser.cc

Index: media/webm/webm_tracks_parser.cc
diff --git a/media/webm/webm_tracks_parser.cc b/media/webm/webm_tracks_parser.cc
index bf039bf77bde53870e56cc3d0564cebde0c74762..811406ae156841747cda2b2b4db07b9b26711c21 100644
--- a/media/webm/webm_tracks_parser.cc
+++ b/media/webm/webm_tracks_parser.cc
@@ -25,6 +25,15 @@ WebMTracksParser::WebMTracksParser()
 
 WebMTracksParser::~WebMTracksParser() {}
 
+const std::string& WebMTracksParser::audio_encryption_key_id() const {
+  if (!audio_content_encodings_client_.get())
+    return EmptyString();
+
+  DCHECK(!audio_content_encodings_client_->content_encodings().empty());
+  return audio_content_encodings_client_->content_encodings()[0]->

[acolwell GONE FROM CHROMIUM, 2012/10/10 16:00:06]

If you only ever use the first encoding, why don't you just store the key_id
string instead of keeping the whole client around? Doing that would greatly
simplify this method since it would become a simple member accessor.

[xhwang, 2012/10/11 00:49:41]

Done.

+      encryption_key_id();
+}
+
 const std::string& WebMTracksParser::video_encryption_key_id() const {
   if (!video_content_encodings_client_.get())
     return EmptyString();