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

win8/metro_driver/display_properties.cc

 // Copyright 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 "stdafx.h"
 
 #include <windows.h>
 #include <wrl\implements.h>
 #include <wrl\wrappers\corewrappers.h>
 #include <windows.foundation.h>
 #include <windows.graphics.display.h>
 #include "base/win/windows_version.h"
-#include "ui/gfx/win/dpi.h"
+#include "ui/gfx/dpi.h"
 #include "winrt_utils.h"
 
 float GetModernUIScale() {
   if (base::win::GetVersion() >= base::win::VERSION_WIN8) {
     Microsoft::WRL::ComPtr<
         ABI::Windows::Graphics::Display::IDisplayPropertiesStatics>
         display_properties;
     if (SUCCEEDED(winrt_utils::CreateActivationFactory(
         RuntimeClass_Windows_Graphics_Display_DisplayProperties,
         display_properties.GetAddressOf()))) {
       ABI::Windows::Graphics::Display::ResolutionScale resolution_scale;
       if (SUCCEEDED(display_properties->get_ResolutionScale(&resolution_scale)))
         return static_cast<float>(resolution_scale) / 100.0f;
     }
   }
   return gfx::GetDPIScale();
 }