Removes most of aura dependencies from DefaultState

ash/wm/aura/wm_globals_aura.cc

Index: ash/wm/aura/wm_globals_aura.cc
diff --git a/ash/wm/aura/wm_globals_aura.cc b/ash/wm/aura/wm_globals_aura.cc
index daa7082bdc251fe6b78ba03dfb8c01a596d4e0c7..f308d936c73544c8194ac4928a89c7c7ff7f04fd 100644
--- a/ash/wm/aura/wm_globals_aura.cc
+++ b/ash/wm/aura/wm_globals_aura.cc
@@ -4,6 +4,7 @@
 
 #include "ash/wm/aura/wm_globals_aura.h"
 
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
@@ -45,6 +46,12 @@ WmWindow* WmGlobalsAura::GetActiveWindow() {
   return WmWindowAura::Get(wm::GetActiveWindow());
 }
 
+WmWindow* WmGlobalsAura::GetRootWindowForDisplayId(int64_t display_id) {
+  return WmWindowAura::Get(Shell::GetInstance()
+                               ->window_tree_host_manager()
+                               ->GetRootWindowForDisplayId(display_id));
+}
+
 WmWindow* WmGlobalsAura::GetRootWindowForNewWindows() {
   return WmWindowAura::Get(Shell::GetTargetRootWindow());
 }