Make sure all paths out of the dialog properly unregister observers.

chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h

Index: chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h
diff --git a/chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h b/chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h
index 76c2033be2c93ebad8ef492fd9ba39a2ce27bc7d..839f0116fcb05be10563f340a7c125e50b76c3c5 100644
--- a/chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h
+++ b/chrome/browser/ui/javascript_dialogs/javascript_dialog_tab_helper.h
@@ -67,10 +67,18 @@ class JavaScriptDialogTabHelper
  private:
   friend class content::WebContentsUserData<JavaScriptDialogTabHelper>;
 
+  // Wrapper around a DialogClosedCallback so that we can intercept it before
+  // passing it onto the original callback.
+  void OnDialogClosed(DialogClosedCallback callback,
+                      bool success,
+                      const base::string16& user_input);
+
   void CloseDialog(bool suppress_callback,
                    bool success,
                    const base::string16& user_input);
 
+  void ClearDialogInfo();
+
   // The dialog being displayed on the observed WebContents.
   base::WeakPtr<JavaScriptDialog> dialog_;