Add NativePixmapHandle type & interface for exporting them

ui/ozone/platform/drm/gpu/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/drm/gpu/gbm_buffer.h"
 
 #include <drm.h>
 #include <fcntl.h>
 #include <gbm.h>
 #include <xf86drm.h>
@@ skipping 76 matching lines @@
 }
 
 void GbmPixmap::SetScalingCallback(const ScalingCallback& scaling_callback) {
   scaling_callback_ = scaling_callback;
 }
 
 scoped_refptr<NativePixmap> GbmPixmap::GetScaledPixmap(gfx::Size new_size) {
   return scaling_callback_.Run(new_size);
 }
 
+bool GbmPixmap::ExportHandle(gfx::NativePixmapHandle* handle) {
+  int dmabuf_fd = dup(dma_buf_);
+  if (dmabuf_fd < 0) {
+    PLOG(ERROR) << "dup";
+    return false;
+  }
+
+  handle->fd = base::FileDescriptor(base::ScopedFD(dmabuf_fd));
+  handle->stride = gbm_bo_get_stride(buffer_->bo());
+  return true;
+}
+
 GbmPixmap::~GbmPixmap() {
   if (dma_buf_ > 0)
     close(dma_buf_);
 }
 
 void* GbmPixmap::GetEGLClientBuffer() {
   return nullptr;
 }
 
 int GbmPixmap::GetDmaBufFd() {
@@ skipping 36 matching lines @@
 
   gfx::Size pixmap_size = buffer_->GetSize();
   // If the required size is not integer-sized, round it to the next integer.
   *required_size = gfx::ToCeiledSize(
       gfx::SizeF(display_bounds.width() / crop_rect.width(),
                  display_bounds.height() / crop_rect.height()));
   return pixmap_size != *required_size;
 }
 
 }  // namespace ui