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

ui/native_theme/native_theme_win.cc

 // Copyright (c) 2012 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/native_theme/native_theme_win.h"
 
 #include <windows.h>
 #include <uxtheme.h>
 #include <vsstyle.h>
 #include <vssym32.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/scoped_hdc.h"
 #include "base/win/scoped_select_object.h"
 #include "base/win/windows_version.h"
 #include "skia/ext/bitmap_platform_device.h"
 #include "skia/ext/platform_canvas.h"
 #include "skia/ext/skia_utils_win.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkColorPriv.h"
 #include "third_party/skia/include/core/SkShader.h"
 #include "ui/gfx/color_utils.h"
+#include "ui/gfx/dpi.h"
 #include "ui/gfx/gdi_util.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_conversions.h"
-#include "ui/gfx/win/dpi.h"
 #include "ui/native_theme/common_theme.h"
 
 // This was removed from Winvers.h but is still used.
 #if !defined(COLOR_MENUHIGHLIGHT)
 #define COLOR_MENUHIGHLIGHT 29
 #endif
 
 namespace {
 
 // TODO: Obtain the correct colors using GetSysColor.
@@ skipping 2020 matching lines @@
     break;
   case LAST:
     NOTREACHED();
     break;
   }
   theme_handles_[theme_name] = handle;
   return handle;
 }
 
 }  // namespace ui