chromeos: convert more ash/wm code to aura::Window

ash/wm/workspace/workspace_event_handler.h

Index: ash/wm/workspace/workspace_event_handler.h
diff --git a/ash/wm/workspace/workspace_event_handler.h b/ash/wm/workspace/workspace_event_handler.h
index d400eeb3d80c71f495ce9e3dc1fda8413916c38b..5c94d040c19a5c6b69610dd78eaee2ca431c521b 100644
--- a/ash/wm/workspace/workspace_event_handler.h
+++ b/ash/wm/workspace/workspace_event_handler.h
@@ -9,13 +9,16 @@
 #include "ash/wm/workspace/multi_window_resize_controller.h"
 #include "base/macros.h"
 
+namespace aura {
+class Window;
+}
+
 namespace ui {
 class GestureEvent;
 class MouseEvent;
 }
 
 namespace ash {
-class WmWindow;
 class WorkspaceEventHandlerTestHelper;
 
 namespace wm {
@@ -31,8 +34,8 @@ class ASH_EXPORT WorkspaceEventHandler {
   WorkspaceEventHandler();
   virtual ~WorkspaceEventHandler();
 
-  void OnMouseEvent(ui::MouseEvent* event, WmWindow* target);
-  void OnGestureEvent(ui::GestureEvent* event, WmWindow* target);
+  void OnMouseEvent(ui::MouseEvent* event, aura::Window* target);
+  void OnGestureEvent(ui::GestureEvent* event, aura::Window* target);
 
  private:
   friend class WorkspaceEventHandlerTestHelper;