drm: GPU process manages VGEM fd.

ui/ozone/platform/drm/gpu/gbm_device.cc

 // Copyright 2015 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_device.h"
 
 #include <gbm.h>
 
 namespace ui {
 
-GbmDevice::GbmDevice(const base::FilePath& device_path)
-    : DrmDevice(device_path), device_(nullptr) {
-}
-
 GbmDevice::GbmDevice(const base::FilePath& device_path, base::File file)
     : DrmDevice(device_path, file.Pass()), device_(nullptr) {
 }
 
 GbmDevice::~GbmDevice() {
   if (device_)
     gbm_device_destroy(device_);
 }
 
 bool GbmDevice::Initialize() {
   if (!DrmDevice::Initialize())
     return false;
 
   device_ = gbm_create_device(get_fd());
   if (!device_) {
     PLOG(ERROR) << "Unable to initialize GBM for " << device_path().value();
     return false;
   }
 
   return true;
 }
 
 }  // namespace ui