Introduce runtime.onSuspendCanceled() event.

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_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 20 matching lines @@
 // only with extensions that have not-yet-loaded lazy background pages.
 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.
+  // the ExtensionHost parameter is NULL. If there is currently a background
+  // page available to handle the task, any suspend the page was in the middle
+  // of will be canceled and the task will be executed with the background page
+  // as an argument. If the extension id isn't lazy, |task| will be executed
+  // straight away.
   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;
 
+  // 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);
+
   void StartLazyBackgroundPage(Profile* profile,
                                const std::string& extension_id);
 
+  // Executes |task| on an existing ExtensionHost if it exists. If the host is
+  // in the middle of a suspend, that suspend is canceled. Returns true if
+  // |task| was executed.
+  bool ExecuteTaskNowIfPossible(Profile* profile,
+                                const std::string& extension_id,
+                                const PendingTask& task);
+
   // 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_