ash: Fix transparency glitches in window header

ash/wm/frame_painter.h

Index: ash/wm/frame_painter.h
diff --git a/ash/wm/frame_painter.h b/ash/wm/frame_painter.h
index 31a52bea9ab2bea92c57d627e34cbf30e0af96b9..c61102e04a0e59449874fc187be112cd8ca918d9 100644
--- a/ash/wm/frame_painter.h
+++ b/ash/wm/frame_painter.h
@@ -110,6 +110,8 @@ class ASH_EXPORT FramePainter : public aura::WindowObserver,
   virtual void OnWindowPropertyChanged(aura::Window* window,
                                        const void* key,
                                        intptr_t old) OVERRIDE;
+  virtual void OnWindowVisibilityChanged(aura::Window* window,
+                                         bool visible) OVERRIDE;
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
 
   // Overridden from ui::AnimationDelegate
@@ -133,6 +135,11 @@ class ASH_EXPORT FramePainter : public aura::WindowObserver,
   // window header.
   static bool UseSoloWindowHeader();
 
+  // Schedules a paint for the window header of the solo window.  Invoke this
+  // when another window is hidden or destroyed to force the transparency of
+  // the now-solo window to update.
+  static void SchedulePaintForSoloWindow();
+
   static std::set<FramePainter*>* instances_;
 
   // Not owned