Allow Forced Scale Factor with Per-Monitor DPI

ui/display/win/screen_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/display/win/screen_win.h"
 
 #include <windows.h>
 #include <shellscalingapi.h>
 
 #include <algorithm>
@@ skipping 17 matching lines @@
 namespace display {
 namespace win {
 namespace {
 
 // TODO(robliao): http://crbug.com/615514 Remove when ScreenWin usage is
 // resolved with Desktop Aura and WindowTreeHost.
 ScreenWin* g_screen_win_instance = nullptr;
 
 float GetMonitorScaleFactor(HMONITOR monitor) {
   DCHECK(monitor);
+  if (display::Display::HasForceDeviceScaleFactor())
+    return display::Display::GetForcedDeviceScaleFactor();
+
   if (base::win::IsProcessPerMonitorDpiAware()) {
     static auto get_dpi_for_monitor_func = [](){
       using GetDpiForMonitorPtr = decltype(::GetDpiForMonitor)*;
       HMODULE shcore_dll = ::LoadLibrary(L"shcore.dll");
       if (shcore_dll) {
         return reinterpret_cast<GetDpiForMonitorPtr>(
                    ::GetProcAddress(shcore_dll, "GetDpiForMonitor"));
       }
       return static_cast<GetDpiForMonitorPtr>(nullptr);
     }();
@@ skipping 514 matching lines @@
     if (std::find(unique_scale_factors.begin(), unique_scale_factors.end(),
                   reported_scale) == unique_scale_factors.end()) {
       unique_scale_factors.push_back(reported_scale);
       UMA_HISTOGRAM_SPARSE_SLOWLY("UI.DeviceScale", reported_scale);
     }
   }
 }
 
 }  // namespace win
 }  // namespace display