VaapiVideoAccelerator: make Vaapi accelerator work with ozone

ui/ozone/platform/dri/gbm_buffer.cc

 // Copyright 2014 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 "ui/ozone/platform/dri/gbm_buffer.h"
 
 #include <gbm.h>
 
 #include "base/logging.h"
 
@@ skipping 53 matching lines @@
 }
 
 GbmPixmap::~GbmPixmap() {
 }
 
 void* GbmPixmap::GetEGLClientBuffer() {
   return buffer_->bo();
 }
 
 int GbmPixmap::GetDmaBufFd() {
-  NOTIMPLEMENTED();
-  return -1;
+  return gbm_bo_get_fd(buffer_->bo());
 }
 
 }  // namespace ui