Make it possible to launch chrome --mash with ozone_platform={wayland|x11}, chromeos=0

chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc

Index: chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc
diff --git a/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc b/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc
index 02f37dac53d32f4dbe758eb583240e1074f78e95..9b3e79e75cc47b8dc7423ec4c47c69d111347030 100644
--- a/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc
+++ b/chrome/browser/ui/views/chrome_browser_main_extra_parts_views.cc
@@ -44,7 +44,7 @@ void ChromeBrowserMainExtraPartsViews::ToolkitInitialized() {
 }
 
 void ChromeBrowserMainExtraPartsViews::PreCreateThreads() {
-#if defined(USE_AURA) && !defined(OS_CHROMEOS)
+#if defined(USE_AURA) && !defined(OS_CHROMEOS) && !defined(USE_OZONE)

[Tom (Use chromium acct), 2016/10/17 23:40:52]

We're definitely going to need an ozone screen at some point, maybe stub one
out?

[tonikitoo, 2016/10/18 04:55:06]

we are using screen_mus.

Calling this as is simply hit an assert in 

FATAL:desktop_factory_ozone.cc(21)] Check failed: impl_. DesktopFactoryOzone
accessed before constructed
#0 0x7f15e92f291e base::debug::StackTrace::StackTrace()
#1 0x7f15e9314940 logging::LogMessage::~LogMessage()
#2 0x7f15e49a36f8 views::DesktopFactoryOzone::GetInstance()
#3 0x7f15e49a3736 views::CreateDesktopScreen()
#4 0x55e5736aa332 ChromeBrowserMainExtraPartsViews::PreCreateThreads()
(..)

I think DesktopFactoryOzone is obsolete.

   // The screen may have already been set in test initialization.
   if (!display::Screen::GetScreen())
     display::Screen::SetScreenInstance(views::CreateDesktopScreen());