Fix a bug where ExtensionHost and ExtensionView weren't getting closed proper...

chrome/browser/extensions/extension_view.h

Index: chrome/browser/extensions/extension_view.h
===================================================================
--- chrome/browser/extensions/extension_view.h	(revision 18385)
+++ chrome/browser/extensions/extension_view.h	(working copy)
@@ -8,6 +8,7 @@
 #include "build/build_config.h"
 
 #include "base/scoped_ptr.h"
+#include "chrome/common/notification_registrar.h"
 #include "googleurl/src/gurl.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "views/controls/native/native_view_host.h"
@@ -28,7 +29,8 @@
 };
 
 // This handles the display portion of an ExtensionHost.
-class ExtensionView : public views::NativeViewHost {
+class ExtensionView : public views::NativeViewHost,
+                      public NotificationObserver {
  public:
   ExtensionView(ExtensionHost* host, Browser* browser);
   ~ExtensionView();
@@ -56,6 +58,11 @@
   virtual void ViewHierarchyChanged(bool is_add,
                                     views::View *parent, views::View *child);
 
+  // NotificationObserver:
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
  private:
   friend class ExtensionHost;
 
@@ -84,6 +91,9 @@
   // Note: the view does not own its container.
   ExtensionContainer* container_;
 
+  // So that we can track browser window closing.
+  NotificationRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionView);
 };