Couple of changes for client area

ui/views/widget/desktop_aura/desktop_window_tree_host.h

Index: ui/views/widget/desktop_aura/desktop_window_tree_host.h
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host.h b/ui/views/widget/desktop_aura/desktop_window_tree_host.h
index b09f96603d6f663eeacb4f92b620216a29cebbd6..e8bfb9df4f47f9fc4ea9764b6d12cf4f892db51e 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host.h
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host.h
@@ -158,6 +158,10 @@ class VIEWS_EXPORT DesktopWindowTreeHost {
 
   // Called when the window's size constraints change.
   virtual void SizeConstraintsChanged() = 0;
+
+  // Returns true if the transparency of the DesktopNativeWidgetAura's
+  // |content_window_| should change.
+  virtual bool ShouldUpdateWindowTransparency() const = 0;
 };
 
 }  // namespace views