media: Add support for playback of VP8 Alpha video streams

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 "base/command_line.h"
 #include "media/base/filter_collection.h"
 #include "media/base/media_switches.h"
@@ skipping 18 matching lines @@
   }
 }
 
 // Constructs and adds the default video decoders to |filter_collection|.
 //
 // Note that decoders in the |filter_collection| are initialized in order.
 static void AddDefaultDecodersToCollection(
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     media::FilterCollection* filter_collection) {
 
-  scoped_refptr<media::FFmpegVideoDecoder> ffmpeg_video_decoder =
-      new media::FFmpegVideoDecoder(message_loop);
-  filter_collection->GetVideoDecoders()->push_back(ffmpeg_video_decoder);
-
   // TODO(phajdan.jr): Remove ifdefs when libvpx with vp9 support is released
   // (http://crbug.com/174287) .
 #if !defined(MEDIA_DISABLE_LIBVPX)
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
-  if (cmd_line->HasSwitch(switches::kEnableVp9Playback)) {
+  if (cmd_line->HasSwitch(switches::kEnableVp9Playback) ||
+      cmd_line->HasSwitch(switches::kEnableVp8AlphaPlayback) ) {
     scoped_refptr<media::VpxVideoDecoder> vpx_video_decoder =
         new media::VpxVideoDecoder(message_loop);
     filter_collection->GetVideoDecoders()->push_back(vpx_video_decoder);
   }
 #endif  // !defined(MEDIA_DISABLE_LIBVPX)
+
+  scoped_refptr<media::FFmpegVideoDecoder> ffmpeg_video_decoder =
+      new media::FFmpegVideoDecoder(message_loop);
+  filter_collection->GetVideoDecoders()->push_back(ffmpeg_video_decoder);
 }
 
 void BuildMediaSourceCollection(
     const scoped_refptr<media::ChunkDemuxer>& demuxer,
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     media::FilterCollection* filter_collection) {
   DCHECK(demuxer);
   filter_collection->SetDemuxer(demuxer);
 
   // Remove GPUVideoDecoder until it supports codec config changes.
   // TODO(acolwell): Remove this once http://crbug.com/151045 is fixed.
   DCHECK_LE(filter_collection->GetVideoDecoders()->size(), 1u);
   filter_collection->GetVideoDecoders()->clear();
 
   AddDefaultDecodersToCollection(message_loop, filter_collection);
 }
 
 void BuildDefaultCollection(
     const scoped_refptr<media::DataSource>& data_source,
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     media::FilterCollection* filter_collection,
     const media::FFmpegNeedKeyCB& need_key_cb) {
   filter_collection->SetDemuxer(new media::FFmpegDemuxer(
       message_loop, data_source, need_key_cb));
 
   AddDefaultDecodersToCollection(message_loop, filter_collection);
 }
 
 }  // webkit_media