Enable hidpi on Linux, refactor a bit on Windows to share

ui/base/win/dpi_setup.cc

Index: ui/base/win/dpi_setup.cc
diff --git a/ui/base/win/dpi_setup.cc b/ui/base/win/dpi_setup.cc
deleted file mode 100644
index 423b788132ac0a3cd5153fd6625d4e6b3b0d20f7..0000000000000000000000000000000000000000
--- a/ui/base/win/dpi_setup.cc
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright (c) 2013 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/base/win/dpi_setup.h"
-
-#include "base/command_line.h"
-#include "ui/base/layout.h"
-#include "ui/gfx/display.h"
-#include "ui/gfx/win/dpi.h"
-
-namespace ui {
-namespace win {
-
-void InitDeviceScaleFactor() {
-  gfx::InitDeviceScaleFactor(gfx::GetDPIScale());
-}
-
-}  // namespace win
-}  // namespace ui