Revert of Ensure compositor initialized before WindowTreeHost is Shown.

ui/aura/window_tree_host.cc

Index: ui/aura/window_tree_host.cc
diff --git a/ui/aura/window_tree_host.cc b/ui/aura/window_tree_host.cc
index a1bac9be53163090c41ee54d31644ad12ae785ce..87fac84f1cfdfdd5241b829cdd23697b119055f6 100644
--- a/ui/aura/window_tree_host.cc
+++ b/ui/aura/window_tree_host.cc
@@ -209,11 +209,8 @@
 }
 
 void WindowTreeHost::Show() {
-  // Ensure that compositor has been properly initialized, see InitCompositor()
-  // and InitHost().
-  DCHECK(compositor());
-  DCHECK_EQ(compositor()->root_layer(), window()->layer());
-  compositor()->SetVisible(true);
+  if (compositor())
+    compositor()->SetVisible(true);
   ShowImpl();
 }