Moves ash/wm/common back into ash

ash/wm/common/wm_display_observer.h

Index: ash/wm/common/wm_display_observer.h
diff --git a/ash/wm/common/wm_display_observer.h b/ash/wm/common/wm_display_observer.h
index 7307c6b1aa6e70cfc4a7e2a217b3e0ad4ca0c15a..e3e9b721204d758ae3a93173ce9db05d9f36aa00 100644
--- a/ash/wm/common/wm_display_observer.h
+++ b/ash/wm/common/wm_display_observer.h
@@ -5,7 +5,7 @@
 #ifndef ASH_WM_COMMON_WM_DISPLAY_OBSERVER_H_
 #define ASH_WM_COMMON_WM_DISPLAY_OBSERVER_H_
 
-#include "ash/wm/common/ash_wm_common_export.h"
+#include "ash/ash_export.h"
 
 namespace ash {
 namespace wm {
@@ -13,7 +13,7 @@ namespace wm {
 class WmWindow;
 
 // Used to track changes in display configuration.
-class ASH_WM_COMMON_EXPORT WmDisplayObserver {
+class ASH_EXPORT WmDisplayObserver {
  public:
   // Called prior to the display configuration changing.
   virtual void OnDisplayConfigurationChanging() {}