Add support for encrypted WebM files as defined in the RFC.

media/filters/ffmpeg_video_decoder.h

Index: media/filters/ffmpeg_video_decoder.h
diff --git a/media/filters/ffmpeg_video_decoder.h b/media/filters/ffmpeg_video_decoder.h
index e52ce2e69397f54474c0e1e8169ff3e243bfeab8..c0ddd0bb50be44788d3020a760948978f53e23cf 100644
--- a/media/filters/ffmpeg_video_decoder.h
+++ b/media/filters/ffmpeg_video_decoder.h
@@ -10,7 +10,7 @@
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/video_decoder.h"
-#include "media/crypto/aes_decryptor.h"
+#include "media/crypto/decryptor.h"
 
 class DecoderBuffer;
 class MessageLoop;
@@ -35,7 +35,7 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
 
   // Must be called prior to initialization if decrypted buffers will be
   // encountered.
-  void set_decryptor(AesDecryptor* decryptor);
+  void set_decryptor(Decryptor* decryptor);
 
  protected:
   virtual ~FFmpegVideoDecoder();
@@ -101,7 +101,7 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
   // Pointer to the demuxer stream that will feed us compressed buffers.
   scoped_refptr<DemuxerStream> demuxer_stream_;
 
-  AesDecryptor* decryptor_;
+  Decryptor* decryptor_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegVideoDecoder);
 };