aura: Rename OnWindowVisisbilityChanged() to OnWindowTargetVisibilityChanged().

ui/aura/window_delegate.h

Index: ui/aura/window_delegate.h
diff --git a/ui/aura/window_delegate.h b/ui/aura/window_delegate.h
index 778311ccba4baf291e349bd5f63b38a464629a9a..6549bed54153852aed94c38d16c578ebb961ab81 100644
--- a/ui/aura/window_delegate.h
+++ b/ui/aura/window_delegate.h
@@ -84,11 +84,10 @@ class AURA_EXPORT WindowDelegate {
   // The delegate can use this as an opportunity to delete itself if necessary.
   virtual void OnWindowDestroyed() = 0;
 
-  // Called when the visibility of a Window changes. See description in
-  // WindowObserver::OnWindowDestroyed() for details.
-  // TODO: this should be renamed to OnWindowTargetVisibilityChanged() to
-  // match when it's sent.
-  virtual void OnWindowVisibilityChanged(bool visible) = 0;
+  // Called when the TargetVisibility() of a Window changes. |visible|
+  // corresponds to the target visibility of the window. See
+  // Window::TargetVisibility() for details.
+  virtual void OnWindowTargetVisibilityChanged(bool visible) = 0;
 
   // Called from Window::HitTest to check if the window has a custom hit test
   // mask. It works similar to the views counterparts. That is, if the function