Revert of p1 mus+ash chrome renders ui and content

ui/views/mus/native_widget_mus.cc

Index: ui/views/mus/native_widget_mus.cc
diff --git a/ui/views/mus/native_widget_mus.cc b/ui/views/mus/native_widget_mus.cc
index 848b78d27661d5ac36f2f8d0bd6ce31b031c83cf..66f38d44fdb7720798cacfc97380b64e78303c8b 100644
--- a/ui/views/mus/native_widget_mus.cc
+++ b/ui/views/mus/native_widget_mus.cc
@@ -256,15 +256,13 @@
   // picked up.
   ui::ContextFactory* default_context_factory =
       aura::Env::GetInstance()->context_factory();
-  // For Chrome, we need the GpuProcessTransportFactory so that renderer and
-  // browser pixels are composited into a single backing
-  // SoftwareOutputDeviceMus.
-  if (!default_context_factory)
-    aura::Env::GetInstance()->set_context_factory(context_factory_.get());
+  aura::Env::GetInstance()->set_context_factory(context_factory_.get());
   window_tree_host_.reset(
       new WindowTreeHostMus(shell_, this, window_, surface_type_));
   window_tree_host_->InitHost();
   aura::Env::GetInstance()->set_context_factory(default_context_factory);
+  DCHECK_EQ(context_factory_.get(),
+            window_tree_host_->compositor()->context_factory());
 
   focus_client_.reset(new wm::FocusController(new FocusRulesImpl));