Support encrypted audio stream in demuxer.

media/webm/webm_tracks_parser.h

Index: media/webm/webm_tracks_parser.h
diff --git a/media/webm/webm_tracks_parser.h b/media/webm/webm_tracks_parser.h
index 24211edb1e8c6b234dc3397f3e1075b028f02e58..02d43d6bd70f6f894d4e07286f97697ba5ffc407 100644
--- a/media/webm/webm_tracks_parser.h
+++ b/media/webm/webm_tracks_parser.h
@@ -29,8 +29,12 @@ class WebMTracksParser : public WebMParserClient {
 
   int64 audio_track_num() const { return audio_track_num_; }
   int64 video_track_num() const { return video_track_num_; }
-
-  const std::string& video_encryption_key_id() const;
+  const std::string& audio_encryption_key_id() const {
+    return audio_encryption_key_id_;
+  }
+  const std::string& video_encryption_key_id() const {
+    return video_encryption_key_id_;
+  }
 
  private:
   // WebMParserClient methods
@@ -46,10 +50,9 @@ class WebMTracksParser : public WebMParserClient {
   scoped_ptr<WebMContentEncodingsClient> track_content_encodings_client_;
 
   int64 audio_track_num_;
-  scoped_ptr<WebMContentEncodingsClient> audio_content_encodings_client_;
-
   int64 video_track_num_;
-  scoped_ptr<WebMContentEncodingsClient> video_content_encodings_client_;
+  std::string audio_encryption_key_id_;
+  std::string video_encryption_key_id_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMTracksParser);
 };