aura: Unify WindowTreeHost for some platforms

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 b698a5f2b72d38fbbd891219e0d789d9172f6d2d..1e0c0e06fe02a85db0a646cb94eee172213ce066 100644
--- a/ui/aura/window_tree_host.cc
+++ b/ui/aura/window_tree_host.cc
@@ -49,17 +49,6 @@ WindowTreeHost::~WindowTreeHost() {
   }
 }
 
-#if defined(OS_ANDROID)
-// static
-WindowTreeHost* WindowTreeHost::Create(const gfx::Rect& bounds) {
-  // This is only hit for tests and ash, right now these aren't an issue so
-  // adding the CHECK.
-  // TODO(sky): decide if we want a factory.
-  CHECK(false);
-  return nullptr;
-}
-#endif
-
 // static
 WindowTreeHost* WindowTreeHost::GetForAcceleratedWidget(
     gfx::AcceleratedWidget widget) {