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

chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.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 "chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h"
 
 #include "base/command_line.h"
 #include "base/run_loop.h"
 #include "chrome/browser/chrome_browser_main.h"
 #include "chrome/browser/ui/aura/active_desktop_monitor.h"
 #include "chrome/browser/ui/host_desktop.h"
 #include "chrome/browser/ui/simple_message_box.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
 #include "ui/aura/env.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/ui_base_switches.h"
+#include "ui/gfx/dpi.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/widget/native_widget_aura.h"
 
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/libgtk2ui/gtk2_ui.h"
 #include "chrome/common/pref_names.h"
 #include "ui/aura/window.h"
 #include "ui/base/ime/input_method_initializer.h"
@@ skipping 57 matching lines @@
 ChromeBrowserMainExtraPartsAura::~ChromeBrowserMainExtraPartsAura() {
 }
 
 void ChromeBrowserMainExtraPartsAura::PreEarlyInitialization() {
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
   if (GetInitialDesktop() != chrome::HOST_DESKTOP_TYPE_ASH) {
     // TODO(erg): Refactor this into a dlopen call when we add a GTK3 port.
     views::LinuxUI* gtk2_ui = BuildGtk2UI();
     gtk2_ui->SetNativeThemeOverride(base::Bind(&GetNativeThemeForWindow));
     views::LinuxUI::SetInstance(gtk2_ui);
+    gfx::InitDeviceScaleFactor(gfx::GetDPIScale());
   } else {
     // TODO(erg): Eventually, we'll need to somehow support IMEs in ash on
     // Linux.
     ui::InitializeInputMethodForTesting();
   }
 #endif
 }
 
 void ChromeBrowserMainExtraPartsAura::ToolkitInitialized() {
 #if !defined(OS_CHROMEOS)
@@ skipping 56 matching lines @@
                            chrome::MESSAGE_BOX_TYPE_WARNING);
 
     // Avoids gpu_process_transport_factory.cc(153)] Check failed:
     // per_compositor_data_.empty() when quit is chosen.
     base::RunLoop().RunUntilIdle();
 
     exit(EXIT_FAILURE);
   }
 }
 #endif