reland r57885 with a fix for linux/views.

chrome/browser/gtk/gtk_util.h

 // Copyright (c) 2010 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 CHROME_BROWSER_GTK_GTK_UTIL_H_
 #define CHROME_BROWSER_GTK_GTK_UTIL_H_
 #pragma once
 
 #include <gtk/gtk.h>
 #include <string>
@@ skipping 297 matching lines @@
 // host window. On Linux, it merely returns the passed in dialog.
 GtkWindow* GetDialogWindow(GtkWidget* dialog);
 
 // Gets dialog window bounds.
 gfx::Rect GetDialogBounds(GtkWidget* dialog);
 
 // Returns the stock menu item label for the "preferences" item - returns an
 // empty string if no stock item found.
 string16 GetStockPreferencesMenuLabel();
 
+// Checks whether a widget is actually visible, i.e. whether it and all its
+// ancestors up to its toplevel are visible.
+bool IsWidgetAncestryVisible(GtkWidget* widget);
+
 }  // namespace gtk_util
 
 #endif  // CHROME_BROWSER_GTK_GTK_UTIL_H_