[1/2][Ozone-Drm] Refactor GPU display management

ui/ozone/platform/drm/gpu/drm_display_mode.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/drm_display_mode.h"
-
-namespace ui {
-
-namespace {
-
-float GetRefreshRate(const drmModeModeInfo& mode) {
-  if (!mode.htotal || !mode.vtotal)
-    return mode.vrefresh;
-
-  float clock = mode.clock;
-  float htotal = mode.htotal;
-  float vtotal = mode.vtotal;
-
-  return (clock * 1000.0f) / (htotal * vtotal);
-}
-
-}  // namespace
-
-DrmDisplayMode::DrmDisplayMode(const drmModeModeInfo& mode)
-    : DisplayMode(gfx::Size(mode.hdisplay, mode.vdisplay),
-                  mode.flags & DRM_MODE_FLAG_INTERLACE,
-                  GetRefreshRate(mode)),
-      mode_info_(mode) {
-}
-
-DrmDisplayMode::~DrmDisplayMode() {
-}
-
-}  // namespace ui