Support external buffer import in VDA interface and add a V4L2SVDA impl.

media/filters/gpu_video_decoder.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 "media/filters/gpu_video_decoder.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 492 matching lines @@
     visible_rect = picture.visible_rect();
   }
   if (!gfx::Rect(pb.size()).Contains(visible_rect)) {
     LOG(WARNING) << "Visible size " << visible_rect.ToString()
                  << " is larger than coded size " << pb.size().ToString();
     visible_rect = gfx::Rect(pb.size());
   }
 
   DCHECK(decoder_texture_target_);
 
-  bool opaque = IsOpaque(config_.format());
-
   scoped_refptr<VideoFrame> frame(VideoFrame::WrapNativeTexture(
-      opaque ? PIXEL_FORMAT_XRGB : PIXEL_FORMAT_ARGB,
+      vda_->GetOutputFormat(),

[kcwu, 2016/03/22 07:47:02]

The original code will use XRGB for some cases. But new code seems no ways to
use XRGB.
Is this correct?

[Pawel Osciak, 2016/03/28 01:31:29]

If a VDA doesn't implement GetOutputFormat(), it will default to XRGB returned
by the implementation in the base class.

[Pawel Osciak, 2016/03/28 01:59:10]

Sorry, I meant ARGB. As for the choice between XRGB and ARGB, we used to have it
as ARGB only. First of all, the VDA has to report the format it produces, as it
is the only entity that knows about it. Further, I believe I discussed this
issue with original author of the change to allow selection, and I believe we
agreed this was preferred. I'll loop back the original author again for a
confirmation.

       gpu::MailboxHolder(pb.texture_mailbox(), gpu::SyncToken(),
                          decoder_texture_target_),
       BindToCurrentLoop(base::Bind(
           &GpuVideoDecoder::ReleaseMailbox, weak_factory_.GetWeakPtr(),
           factories_, picture.picture_buffer_id(), pb.texture_id())),
       pb.size(), visible_rect, natural_size, timestamp));
   if (!frame) {
     DLOG(ERROR) << "Create frame failed for: " << picture.picture_buffer_id();
     NotifyError(VideoDecodeAccelerator::PLATFORM_FAILURE);
     return;
@@ skipping 192 matching lines @@
   }
   return false;
 }
 
 void GpuVideoDecoder::DCheckGpuVideoAcceleratorFactoriesTaskRunnerIsCurrent()
     const {
   DCHECK(factories_->GetTaskRunner()->BelongsToCurrentThread());
 }
 
 }  // namespace media