Add video decoding methods in Decryptor and add DecryptingVideoDecoder.

webkit/media/filter_helpers.cc

Index: webkit/media/filter_helpers.cc
diff --git a/webkit/media/filter_helpers.cc b/webkit/media/filter_helpers.cc
index 9740de48646627cd2d0ac04b0e2e58edb0d717d6..ee3431d1d5a094fb00cb3eb2939a87414ed45814 100644
--- a/webkit/media/filter_helpers.cc
+++ b/webkit/media/filter_helpers.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "media/base/filter_collection.h"
 #include "media/base/message_loop_factory.h"
+#include "media/crypto/decrypting_video_decoder.h"
 #include "media/filters/chunk_demuxer.h"
 #include "media/filters/dummy_demuxer.h"
 #include "media/filters/ffmpeg_audio_decoder.h"
@@ -27,12 +28,21 @@ static void AddDefaultDecodersToCollection(
                  base::Unretained(message_loop_factory),
                  media::MessageLoopFactory::kDecoder)));
 
+  scoped_refptr<media::DecryptingVideoDecoder> decrypting_video_decoder =
+      new media::DecryptingVideoDecoder(
+          base::Bind(&media::MessageLoopFactory::GetMessageLoop,
+                     base::Unretained(message_loop_factory),
+                     media::MessageLoopFactory::kDecoder),
+          decryptor);
+
   scoped_refptr<media::FFmpegVideoDecoder> ffmpeg_video_decoder =
       new media::FFmpegVideoDecoder(
           base::Bind(&media::MessageLoopFactory::GetMessageLoop,
                      base::Unretained(message_loop_factory),
                      media::MessageLoopFactory::kDecoder),
           decryptor);
+
+  filter_collection->GetVideoDecoders()->push_back(decrypting_video_decoder);

[ddorwin, 2012/09/21 00:36:08]

Does this order mean we will never decrypt with HW decoding enabled? I guess
there isn't much we can do until you address your comment below since the GVD is
provided outside this class

[xhwang, 2012/09/25 23:52:32]

Not in this CL. Will enable encrypt-only + GVD/FFVD later.

   filter_collection->GetVideoDecoders()->push_back(ffmpeg_video_decoder);

[xhwang, 2012/09/20 23:26:34]

After this change, we have 3 VideoDecoders in the list (in the following order):
GVD: only accepts unencrypted stream
DVD: only accepts encrypted stream (decrypt-and-decode)
FFVD: accepts both unencrypted and encrypted stream (decrypt-only).

In later CLs decrypt-only will be moved from FFVD to DVD.

[ddorwin, 2012/09/21 00:36:08]

It's not obvious here how the correct one will be selected, especially wrt
is_encrypted(). Probably worth an overall design comment somewhere.

[xhwang, 2012/09/25 23:52:32]

Added more comments for AddDecaultDecodersToCollection() to clarify this. Not
sure it's the best place for these comments though.

 }