Aura: New window shadows, desktop background debug toggle

ash/wm/shadow.h

Index: ash/wm/shadow.h
diff --git a/ash/wm/shadow.h b/ash/wm/shadow.h
index d16021f77881ef32e81e966515aba6ae0d0d7576..82226618ed38d6c9041c244843cbd0da457ace4c 100644
--- a/ash/wm/shadow.h
+++ b/ash/wm/shadow.h
@@ -9,6 +9,7 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ash/ash_export.h"
+#include "ui/gfx/compositor/layer_animation_observer.h"
 #include "ui/gfx/rect.h"
 
 namespace ui {
@@ -21,11 +22,21 @@ namespace internal {
 class ImageGrid;
 
 // Simple class that draws a drop shadow around content at given bounds.
-class ASH_EXPORT Shadow {
+class ASH_EXPORT Shadow : public ui::ImplicitAnimationObserver {
  public:
+  enum Style {
+    // Active windows have more opaque shadows, shifted down to make the window
+    // appear "higher".
+    STYLE_ACTIVE,
+    // Inactive windows have less opaque shadows.
+    STYLE_INACTIVE,
+  };
+
   Shadow();
   ~Shadow();
 
+  void Init();
+
   // 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()
   // should be used to adjust the shadow's size and position (rather than
@@ -33,13 +44,28 @@ class ASH_EXPORT Shadow {
   ui::Layer* layer() const;
 
   const gfx::Rect& content_bounds() const { return content_bounds_; }
-
-  void Init();
+  Style style() const { return style_; }
 
   // Moves and resizes |image_grid_| to frame |content_bounds|.
   void SetContentBounds(const gfx::Rect& content_bounds);
 
+  // Sets the shadow's style, animating opacity as necessary.
+  void SetStyle(Style style);
+
+  // ui::ImplicitAnimationObserver overrides:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE;
+
  private:
+  // Updates the |image_grid_| images to the current |style_|.
+  void UpdateImagesForStyle();
+
+  // Updates the |image_grid_| bounds based on its image sizes and the
+  // current |content_bounds_|.
+  void UpdateImageGridBounds();
+
+  // The current style, set when the transition animation starts.
+  Style style_;
+
   scoped_ptr<ImageGrid> image_grid_;
 
   // Bounds of the content that the shadow encloses.