Have LazyBackgroundTaskQueue notify consumers when the transient page fails to

chrome/browser/extensions/lazy_background_task_queue.h

 // Copyright (c) 2012 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_EXTENSIONS_LAZY_BACKGROUND_TASK_QUEUE_H_
 #define CHROME_BROWSER_EXTENSIONS_LAZY_BACKGROUND_TASK_QUEUE_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 22 matching lines @@
 
   explicit LazyBackgroundTaskQueue(Profile* profile);
   virtual ~LazyBackgroundTaskQueue();
 
   // Returns true if the task should be added to the queue (that is, if the
   // extension has a lazy background page that isn't ready yet).
   bool ShouldEnqueueTask(Profile* profile, const Extension* extension);
 
   // 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.
   void AddPendingTask(
       Profile* profile,
       const std::string& extension_id,
       const PendingTask& task);
 
  private:
   // A map between an extension_id,Profile pair and the queue of tasks pending
   // the load of its background page.
   typedef std::string ExtensionID;
   typedef std::pair<Profile*, ExtensionID> PendingTasksKey;
   typedef std::vector<PendingTask> PendingTasksList;
   typedef std::map<PendingTasksKey,
                    linked_ptr<PendingTasksList> > PendingTasksMap;
 
   // content::NotificationObserver interface.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
-  // Called when a lazy background page has finished loading. All enqueued
-  // tasks are run in order.
-  void ProcessPendingTasks(ExtensionHost* host);
+  // Called when a lazy background page has finished loading, or has failed to
+  // load (host is NULL in that case). All enqueued tasks are run in order.
+  void ProcessPendingTasks(
+      ExtensionHost* host,
+      Profile* profile,
+      const Extension* extension);
 
   Profile* profile_;
   content::NotificationRegistrar registrar_;
   PendingTasksMap pending_tasks_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_LAZY_BACKGROUND_TASK_QUEUE_H_