Add video decoding methods in Decryptor and add DecryptingVideoDecoder.

webkit/media/filter_helpers.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/media/filter_helpers.h"
 
 #include "base/bind.h"
 #include "media/base/filter_collection.h"
 #include "media/base/message_loop_factory.h"
+#include "media/filters/decrypting_video_decoder.h"
 #include "media/filters/chunk_demuxer.h"
 #include "media/filters/dummy_demuxer.h"
 #include "media/filters/ffmpeg_audio_decoder.h"
 #include "media/filters/ffmpeg_demuxer.h"
 #include "media/filters/ffmpeg_video_decoder.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURL.h"
 #include "webkit/media/media_stream_client.h"
 
 namespace webkit_media {
 
 // Constructs and adds the default audio/video decoders to |filter_collection|.
+// Note that decoders in the |filter_collection| are ordered. The first
+// audio/video decoder in the |filter_collection| that supports the input
+// audio/video stream will be selected as the audio/video decoder in the media
+// pipeline. This is done by trying to initialize the decoder with the input
+// stream. Some decoder may only accept certain types of streams. For example,
+// DecryptingVideoDecoder only supports encrypted video stream.
 static void AddDefaultDecodersToCollection(
     media::MessageLoopFactory* message_loop_factory,
     media::FilterCollection* filter_collection,
     media::Decryptor* decryptor) {
   filter_collection->AddAudioDecoder(new media::FFmpegAudioDecoder(
       base::Bind(&media::MessageLoopFactory::GetMessageLoop,
                  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);
   filter_collection->GetVideoDecoders()->push_back(ffmpeg_video_decoder);
 }
 
 bool BuildMediaStreamCollection(const WebKit::WebURL& url,
                                 MediaStreamClient* client,
                                 media::MessageLoopFactory* message_loop_factory,
                                 media::FilterCollection* filter_collection) {
   if (!client)
     return false;
 
@@ skipping 38 matching lines @@
   filter_collection->SetDemuxer(new media::FFmpegDemuxer(
       message_loop_factory->GetMessageLoop(
           media::MessageLoopFactory::kPipeline),
       data_source));
 
   AddDefaultDecodersToCollection(message_loop_factory, filter_collection,
                                  decryptor);
 }
 
 }  // webkit_media