Fix Pango font rendering with HiDPi displays on Linux.

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"
@@ skipping 105 matching lines @@
     views::LinuxUI::instance()->Initialize();
 #endif
 }
 
 void ChromeBrowserMainExtraPartsAura::PreCreateThreads() {
 #if !defined(OS_CHROMEOS)
 #if defined(USE_ASH)
   if (!chrome::ShouldOpenAshOnStartup())
 #endif
   {
-    gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE,
-                                   views::CreateDesktopScreen());
+    gfx::Screen* screen = views::CreateDesktopScreen();
+    gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, screen);
+#if defined(USE_X11)
+    views::LinuxUI::instance()->UpdateDeviceScaleFactor(
+        screen->GetPrimaryDisplay().device_scale_factor());
+#endif
   }
 #endif
 }
 
 void ChromeBrowserMainExtraPartsAura::PreProfileInit() {
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
   // Now that we have some minimal ui initialized, check to see if we're
   // running as root and bail if we are.
   DetectRunningAsRoot();
 #endif
@@ skipping 27 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