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 104 matching lines @@
   if (GetInitialDesktop() != chrome::HOST_DESKTOP_TYPE_ASH)
     views::LinuxUI::instance()->Initialize();
 #endif
 }
 
 void ChromeBrowserMainExtraPartsAura::PreCreateThreads() {
 #if !defined(OS_CHROMEOS)
 #if defined(USE_ASH)
   if (!chrome::ShouldOpenAshOnStartup())
 #endif
   {

[Daniel Erat, 2015/03/16 13:57:53]

the code that creates LinuxUI in
chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc looks like it's
hidden behind this:

#if defined(USE_X11) && !defined(OS_CHROMEOS)
  if (GetInitialDesktop() != chrome::HOST_DESKTOP_TYPE_ASH) {

this is already behind !OS_CHROMEOS, but it seems like you should have the rest
of it here.

[stapelberg, 2015/03/17 08:36:33]

Done.

-    gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE,
-                                   views::CreateDesktopScreen());
+    gfx::Screen* screen = views::CreateDesktopScreen();
+    gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, screen);
+    views::LinuxUI *gtk2_ui = views::LinuxUI::instance();

[Daniel Erat, 2015/03/16 13:57:53]

nit: '*' goes to left of space

[stapelberg, 2015/03/17 08:36:33]

Done.

+    CHECK(gtk2_ui);

[Daniel Erat, 2015/03/16 13:57:53]

i'd just inline the views::LinuxUI::instance() where you use it below to keep
the code simpler; it doesn't look like this should ever be null.

[stapelberg, 2015/03/17 08:36:33]

Done.

+    gfx::Display display = screen->GetPrimaryDisplay();
+    CHECK(display.is_valid());

[Daniel Erat, 2015/03/16 13:57:53]

i don't see how it can ever be invalid.

[stapelberg, 2015/03/17 08:36:33]

Done.

+    gtk2_ui->UpdateDeviceScaleFactor(display.device_scale_factor());
   }
 #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