Makes WorkspaceWindowResizer use ash/wm/common types

ash/wm/window_resizer.h

Index: ash/wm/window_resizer.h
diff --git a/ash/wm/window_resizer.h b/ash/wm/window_resizer.h
index 39a47a8b40a3f0a2ed5740bcab7490a2c33f06ca..2ca6f2a232559f310cf7cddf7647baa328533984 100644
--- a/ash/wm/window_resizer.h
+++ b/ash/wm/window_resizer.h
@@ -108,11 +108,10 @@ class ASH_EXPORT WindowResizer {
   DISALLOW_COPY_AND_ASSIGN(WindowResizer);
 };
 
-// Creates a WindowResizer for |window|. This can return a scoped_ptr
-// initialized with NULL if |window| should not be resized nor dragged.
-// TODO(sky): move this to its own file. This is aura specific.
+// Creates a WindowResizer for |window|. Returns a unique_ptr with null if
+// |window| should not be resized nor dragged.
 ASH_EXPORT std::unique_ptr<WindowResizer> CreateWindowResizer(
-    aura::Window* window,
+    wm::WmWindow* window,
     const gfx::Point& point_in_parent,
     int window_component,
     aura::client::WindowMoveSource source);