Fix bug where transient pages would miss events dispatched while it was

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 <set>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/callback_forward.h"
 #include "base/memory/linked_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 class Extension;
 class ExtensionHost;
 class Profile;
 
 namespace extensions {
 
 // This class maintains a queue of tasks that should execute when an
 // extension's lazy background page is loaded. It is also in charge of loading
 // the page when the first task is queued.
 //
 // It is the consumer's responsibility to use this class when appropriate, i.e.
 // only with extensions that have not-yet-loaded lazy background pages.
-class LazyBackgroundTaskQueue : public content::NotificationObserver {
+class LazyBackgroundTaskQueue
+    : public content::NotificationObserver,
+      public base::SupportsWeakPtr<LazyBackgroundTaskQueue> {
  public:
   typedef base::Callback<void(ExtensionHost*)> PendingTask;
 
   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;
+  typedef std::set<PendingTasksKey> PendingPageLoadList;
+
+  void StartLazyBackgroundPage(Profile* profile,
+                               const std::string& extension_id);
 
   // 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, 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_;
+  PendingPageLoadList pending_page_loads_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_LAZY_BACKGROUND_TASK_QUEUE_H_