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..a8721169d8788384038be6818273704562ba0b73 100644
--- a/media/webm/webm_tracks_parser.cc
+++ b/media/webm/webm_tracks_parser.cc
@@ -25,15 +25,6 @@ WebMTracksParser::WebMTracksParser()
 
 WebMTracksParser::~WebMTracksParser() {}
 
-const std::string& WebMTracksParser::video_encryption_key_id() const {
-  if (!video_content_encodings_client_.get())
-    return EmptyString();
-
-  DCHECK(!video_content_encodings_client_->content_encodings().empty());
-  return video_content_encodings_client_->content_encodings()[0]->
-      encryption_key_id();
-}
-
 int WebMTracksParser::Parse(const uint8* buf, int size) {
   track_type_ =-1;
   track_num_ = -1;
@@ -50,7 +41,6 @@ int WebMTracksParser::Parse(const uint8* buf, int size) {
   return parser.IsParsingComplete() ? result : 0;
 }
 
-
 WebMParserClient* WebMTracksParser::OnListStart(int id) {
   if (id == kWebMIdContentEncodings) {
     DCHECK(!track_content_encodings_client_.get());
@@ -81,23 +71,33 @@ bool WebMTracksParser::OnListEnd(int id) {
       return false;
     }
 
-    if (track_type_ == kWebMTrackTypeVideo) {
-      video_track_num_ = track_num_;
-      if (track_content_encodings_client_.get()) {
-        video_content_encodings_client_ =
-            track_content_encodings_client_.Pass();
-      }
-    } else if (track_type_ == kWebMTrackTypeAudio) {
-      audio_track_num_ = track_num_;
-      if (track_content_encodings_client_.get()) {
-        audio_content_encodings_client_ =
-            track_content_encodings_client_.Pass();
-      }
-    } else {
+    if (track_type_ != kWebMTrackTypeAudio &&
+        track_type_ != kWebMTrackTypeVideo) {
       DVLOG(1) << "Unexpected TrackType " << track_type_;
       return false;
     }
 
+    // WebM file should have at most one ContentEncoding element, whose
+    // encoding type must be "encryption".
+    // See: http://wiki.webmproject.org/encryption/webm-encryption-rfc
+    std::string encryption_key_id;
+    if (track_content_encodings_client_.get()) {
+      DCHECK_EQ(track_content_encodings_client_->content_encodings().size(),
+                1u);

[acolwell GONE FROM CHROMIUM, 2012/10/11 16:50:33]

This will cause files w/ multiple content encodings to crash in debug builds and
get accepted in release builds. This doesn't seem right. I think we should
either always allow them and simply add a DVLOG() to indicate that we are
picking the first one when multiple encodings exist or explicitly reject them as
invalid content.

+      const ContentEncoding* content_encoding =
+          track_content_encodings_client_->content_encodings()[0];
+      DCHECK_EQ(content_encoding->type(), ContentEncoding::kTypeEncryption);
+      encryption_key_id = content_encoding->encryption_key_id();
+    }
+
+    if (track_type_ == kWebMTrackTypeAudio) {
+      audio_track_num_ = track_num_;
+      audio_encryption_key_id_ = encryption_key_id;
+    } else if (track_type_ == kWebMTrackTypeVideo) {
+      video_track_num_ = track_num_;
+      video_encryption_key_id_ = encryption_key_id;
+    }
+
     track_type_ = -1;
     track_num_ = -1;
     track_content_encodings_client_.reset();