aura: Draw drop shadows under browsers and menus.

ui/aura/window.h

Index: ui/aura/window.h
diff --git a/ui/aura/window.h b/ui/aura/window.h
index 485bcb41b5ea3b6a7df52550b665eb843546f619..b0dabe9daa978d78e859a4b9fccf5a39cd82bbba 100644
--- a/ui/aura/window.h
+++ b/ui/aura/window.h
@@ -46,6 +46,7 @@ class WindowObserver;
 
 namespace internal {
 class FocusManager;
+class Shadow;
 }
 
 // Aura window implementation. Interesting events are sent to the
@@ -90,6 +91,9 @@ class AURA_EXPORT Window : public ui::LayerDelegate {
   void set_user_data(void* user_data) { user_data_ = user_data; }
   void* user_data() const { return user_data_; }
 
+  // Just made available for tests; outside callers shouldn't need to modify it.
+  const internal::Shadow* shadow() const { return shadow_.get(); }
+
   // Changes the visibility of the window.
   void Show();
   void Hide();
@@ -265,6 +269,11 @@ class AURA_EXPORT Window : public ui::LayerDelegate {
   void* GetProperty(const char* name) const;
   int GetIntProperty(const char* name) const;
 
+  // Sets whether a drop shadow should be displayed around this window or not.
+  // By default, shadows aren't displayed.  It's safe to call this method before
+  // calling Init().
+  void SetShadowVisible(bool visible);
+
  protected:
   // Returns the desktop or NULL if we aren't yet attached to a desktop.
   virtual Desktop* GetDesktop();
@@ -300,6 +309,9 @@ class AURA_EXPORT Window : public ui::LayerDelegate {
                             bool return_tightest,
                             bool for_event_handling);
 
+  // Initialize |shadow_|.  Init() must be called first.
+  void InitShadow();
+
   // Overridden from ui::LayerDelegate:
   virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE;
 
@@ -349,6 +361,12 @@ class AURA_EXPORT Window : public ui::LayerDelegate {
   // implementation.
   std::map<const char*, void*> prop_map_;
 
+  // NULL if SetShadowVisible(true) has never been called.
+  scoped_ptr<internal::Shadow> shadow_;

[sky, 2011/11/15 04:49:13]

Would it work to make the shadow a transient child that is stacked below rather
than above the window?

+
+  // Is |shadow_| currently being shown?
+  bool show_shadow_;
+
   DISALLOW_COPY_AND_ASSIGN(Window);
 };