Fix a crash that happens when changing themes.

chrome/browser/gtk/nine_box.h

 // Copyright (c) 2009 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_NINE_BOX_H_
 #define CHROME_BROWSER_GTK_NINE_BOX_H_
 
 #include <gtk/gtk.h>
 
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_registrar.h"
+#include "chrome/common/notification_type.h"
+
 class ThemeProvider;
 
 // A NineBox manages a set of source images representing a 3x3 grid, where
 // non-corner images can be tiled to make a larger image.  It's used to
 // use bitmaps for constructing image-based resizable widgets like buttons.
 //
 // If you want just a vertical image that stretches in height but is fixed
 // in width, only pass in images for the left column (leave others NULL).
 // Similarly, for a horizontal image that stretches in width but is fixed in
 // height, only pass in images for the top row.
 //
 // TODO(port): add support for caching server-side pixmaps of prerendered
 // nineboxes.
-class NineBox {
+class NineBox : public NotificationObserver {
  public:
   // Construct a NineBox with nine images.  Images are specified using resource
   // ids that will be passed to the resource bundle.  Use 0 for no image.
   NineBox(int top_left, int top, int top_right, int left, int center, int right,
           int bottom_left, int bottom, int bottom_right);
 
   // Same as above, but use themed images.
   NineBox(ThemeProvider* theme_provider,
           int top_left, int top, int top_right, int left, int center, int right,
           int bottom_left, int bottom, int bottom_right);
@@ skipping 11 matching lines @@
   // Change all pixels that are white in |images_| to have 0 opacity.
   void ChangeWhiteToTransparent();
 
   // Set the shape of |widget| to match that of the ninebox. Note that |widget|
   // must have its own window and be allocated. Also, currently only the top
   // three images are used.
   // TODO(estade): extend this function to use all 9 images (if it's ever
   // needed).
   void ContourWidget(GtkWidget* widget) const;
 
+  // Provide NotificationObserver implementation.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
  private:
   GdkPixbuf* images_[9];
+
+  // We need to remember the image ids that the user passes in and the theme
+  // provider so we can reload images if the user changes theme.
+  int image_ids_[9];
+  ThemeProvider* theme_provider_;
+
+  // Used to listen for theme change notifications.
+  NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_GTK_NINE_BOX_H_