Cleanup: remove redundant tab close observation from TabModalConfirmDialogDelegate

chrome/browser/ui/tab_modal_confirm_dialog_delegate.h

Index: chrome/browser/ui/tab_modal_confirm_dialog_delegate.h
diff --git a/chrome/browser/ui/tab_modal_confirm_dialog_delegate.h b/chrome/browser/ui/tab_modal_confirm_dialog_delegate.h
index 4f20b0757a4f2634ac0c80271ed597aeb5b098f0..29413a1242378804f462ef336493701086b90dc0 100644
--- a/chrome/browser/ui/tab_modal_confirm_dialog_delegate.h
+++ b/chrome/browser/ui/tab_modal_confirm_dialog_delegate.h
@@ -8,8 +8,6 @@
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/strings/string16.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "ui/base/window_open_disposition.h"
 
 namespace content {
@@ -36,9 +34,9 @@ class TabModalConfirmDialogOperationsDelegate {
 
 // This class acts as the delegate for a simple tab-modal dialog confirming
 // whether the user wants to execute a certain action.
-class TabModalConfirmDialogDelegate : public content::NotificationObserver {
+class TabModalConfirmDialogDelegate {
  public:
-  explicit TabModalConfirmDialogDelegate(content::WebContents* web_contents);
+  TabModalConfirmDialogDelegate();
   virtual ~TabModalConfirmDialogDelegate();
 
   void set_operations_delegate(
@@ -89,14 +87,6 @@ class TabModalConfirmDialogDelegate : public content::NotificationObserver {
     return operations_delegate_;
   }
 
-  // content::NotificationObserver implementation.
-  // Watch for a closed tab and dismiss the dialog if it occurs.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
-  content::NotificationRegistrar registrar_;
-
  private:
   // It is guaranteed that exactly one of |OnAccepted|, |OnCanceled| or
   // |OnLinkClicked| is eventually called. These method are private to