Add is_encrypted() in VideoDecoderConfig.

media/base/demuxer_stream.h

Index: media/base/demuxer_stream.h
diff --git a/media/base/demuxer_stream.h b/media/base/demuxer_stream.h
index 30ef1ec7e6cbda97fe2417b6de538501b21f5ec3..87b2e160cae2ef37e3b2b8b937b4a88977764bf3 100644
--- a/media/base/demuxer_stream.h
+++ b/media/base/demuxer_stream.h
@@ -67,6 +67,11 @@ class MEDIA_EXPORT DemuxerStream
   // Returns the type of stream.
   virtual Type type() = 0;
 
+  // Returns whether the stream is potentially encrypted.
+  // Note that in a potentially encrypted video stream, individual buffers
+  // can be encrypted or not encrypted.
+  virtual bool is_encrypted() = 0;

[acolwell GONE FROM CHROMIUM, 2012/09/15 00:25:24]

Why is this method necessary especially if it only signals that the content "is
potentially encrypted". It seems to me that the ChunkDemuxerStream should always
return true for this since it never knows when an encrypted initialization
segment could get appended.

[ddorwin, 2012/09/15 00:39:40]

Seems there should be some better indication of "potential", though I don't have
a concise suggestion.
is_potentially_encrypted(), has_encrypted_blocks(), may_be_encrypted().

[ddorwin, 2012/09/15 00:39:40]

We reinitialize decoders when the config changes between segments, right? That
would fit with the broader goal, which is to know whether we need to use a CDM
for decoding during initialization.

[ddorwin, 2012/09/15 03:12:04]

After discussing this offline, I remembered that we decided that the decoder
must be selected once and used for the lifetime of the stream. The plan is to
enforce this in the spec, but for v0.1 we need some help to determine that we
should wait before initializing the decoder. That's where is_encrypted() comes
in.

So, addressing the initial comment:
1) We will not support that use case for now.
2) We hope to eliminate the need for this in the future.

+
   virtual void EnableBitstreamConverter() = 0;
 
  protected: