ui: Cleanup class/struct forward declarations

ash/common/wm_window_property.h

Index: ash/common/wm_window_property.h
diff --git a/ash/common/wm_window_property.h b/ash/common/wm_window_property.h
index b5108836da5ef2c9fb3c5d0001777fe4a9eb2478..732adb8e2c6fdc358706ddd62a58d6977eb57c56 100644
--- a/ash/common/wm_window_property.h
+++ b/ash/common/wm_window_property.h
@@ -7,7 +7,6 @@
 
 namespace ash {
 
-// See ui/aura/client/aura_constants.h for some more detailed descriptions.
 enum class WmWindowProperty {
   // Not a valid property; used for property key translation purposes.
   INVALID_PROPERTY,
@@ -15,15 +14,6 @@ enum class WmWindowProperty {
   // Type bool.
   ALWAYS_ON_TOP,
 
-  // Type ImageSkia.
-  APP_ICON,
-
-  // Type std::string.
-  APP_ID,
-
-  // Type bool.
-  DRAW_ATTENTION,
-
   // Type bool. See aura::client:kExcludeFromMruKey for details.
   EXCLUDE_FROM_MRU,
 
@@ -47,9 +37,6 @@ enum class WmWindowProperty {
 
   // Type int. See aura::client::kTopViewInset for details.
   TOP_VIEW_INSET,
-
-  // Type ImageSkia.
-  WINDOW_ICON,
 };
 
 }  // namespace ash