MacViews: Suppress visibility changes during an asynchronous close.

ui/views/cocoa/views_nswindow_close_animator.h

Index: ui/views/cocoa/views_nswindow_close_animator.h
diff --git a/ui/views/cocoa/views_nswindow_close_animator.h b/ui/views/cocoa/views_nswindow_close_animator.h
new file mode 100644
index 0000000000000000000000000000000000000000..d6b9a0db1e51e5ecd1df07ea01e68ab2479c84d0
--- /dev/null
+++ b/ui/views/cocoa/views_nswindow_close_animator.h
@@ -0,0 +1,18 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_VIEWS_COCOA_VIEWS_NSWINDOW_CLOSE_ANIMATOR_H_
+#define UI_VIEWS_COCOA_VIEWS_NSWINDOW_CLOSE_ANIMATOR_H_
+
+@class NSWindow;
+
+namespace views {
+
+// Spawns a self-owning animation delegate that starts a hide animation, then
+// calls -[NSWindow close] when the animation ends, releasing itself.
+void CloseNativeWindowWithAnimation(NSWindow* window);
+
+}  // namespace views
+
+#endif  // UI_VIEWS_COCOA_VIEWS_NSWINDOW_CLOSE_ANIMATOR_H_