Don't try to load an event page to fire an event if the browser is shutting down.

chrome/browser/extensions/lazy_background_task_queue.h

Index: chrome/browser/extensions/lazy_background_task_queue.h
diff --git a/chrome/browser/extensions/lazy_background_task_queue.h b/chrome/browser/extensions/lazy_background_task_queue.h
index dd612185217cafc41cf7a2c17376106c91df16cf..cb302f8293ae4344ac3d141c5fe6b369a009075b 100644
--- a/chrome/browser/extensions/lazy_background_task_queue.h
+++ b/chrome/browser/extensions/lazy_background_task_queue.h
@@ -42,8 +42,8 @@ class LazyBackgroundTaskQueue : public content::NotificationObserver {
   // Adds a task to the queue for a given extension. If this is the first
   // task added for the extension, its lazy background page will be loaded.
   // The task will be called either when the page is loaded, or when the
-  // page fails to load for some reason (e.g. a crash). In the latter case,
-  // the ExtensionHost parameter is NULL.
+  // page fails to load for some reason (e.g. a crash or browser
+  // shutdown). In the latter case, the ExtensionHost parameter is NULL.
   void AddPendingTask(
       Profile* profile,
       const std::string& extension_id,