Move DIP translation from ui/aura to ui/compositor

ash/wm/shadow.h

Index: ash/wm/shadow.h
diff --git a/ash/wm/shadow.h b/ash/wm/shadow.h
index ae00a4d418c08b83fb92d49b3bdc2cb6d9661d0b..8f5ab0726d743a1908f14e236959ef86dd3ebafa 100644
--- a/ash/wm/shadow.h
+++ b/ash/wm/shadow.h
@@ -12,10 +12,6 @@
 #include "ui/gfx/compositor/layer_animation_observer.h"
 #include "ui/gfx/rect.h"
 
-namespace aura {
-class Window;
-}  // namespace aura
-
 namespace ui {
 class Layer;
 }  // namespace ui
@@ -44,11 +40,7 @@ class ASH_EXPORT Shadow : public ui::ImplicitAnimationObserver {
   Shadow();
   virtual ~Shadow();
 
-  // |window| is a possibly-arbitrary window that is drawn at the same DPI
-  // (i.e. on the same monitor) as this shadow. The actual bounds for the
-  // shadow still has to be provided through |SetContentBounds()|.
-  // TODO(oshima): move scale factor to gfx/compositor and remove this.
-  void Init(aura::Window* window, Style style);
+  void Init(Style style);
 
   // Returns |image_grid_|'s ui::Layer.  This is exposed so it can be added to
   // the same layer as the content and stacked below it.  SetContentBounds()