MacViews: Attach child windows when parent is on the screen.

ui/views/cocoa/views_nswindow_delegate.mm

Index: ui/views/cocoa/views_nswindow_delegate.mm
diff --git a/ui/views/cocoa/views_nswindow_delegate.mm b/ui/views/cocoa/views_nswindow_delegate.mm
index 75346a6a8076dadb929abc2f858e5a2cf57e6892..a9ea7bfd302cd904ba14e53fe48b1298325a8b27 100644
--- a/ui/views/cocoa/views_nswindow_delegate.mm
+++ b/ui/views/cocoa/views_nswindow_delegate.mm
@@ -35,18 +35,10 @@
   [parent_->ns_window() resetCursorRects];
 }
 
-- (void)onWindowOrderWillChange:(NSWindowOrderingMode)orderingMode {
-  parent_->OnVisibilityChangedTo(orderingMode != NSWindowOut);
-}
-
 - (void)onWindowOrderChanged:(NSNotification*)notification {
   parent_->OnVisibilityChanged();
 }
 
-- (void)onWindowWillDisplay {
-  parent_->OnVisibilityChangedTo(true);
-}
-
 - (void)sheetDidEnd:(NSWindow*)sheet
          returnCode:(NSInteger)returnCode
         contextInfo:(void*)contextInfo {