extensions/browser/lazy_background_task_queue.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_
   6 #define EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/callback_forward.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/gtest_prod_util.h"
  14 #include "base/memory/linked_ptr.h"
  15 #include "content/public/browser/notification_observer.h"
  16 #include "content/public/browser/notification_registrar.h"
  17
  18 namespace content {
  19 class BrowserContext;
  20 }
  21
  22 namespace extensions {
  23 class Extension;
  24 class ExtensionHost;
  25
  26 // This class maintains a queue of tasks that should execute when an
  27 // extension's lazy background page is loaded. It is also in charge of loading
  28 // the page when the first task is queued.
  29 //
  30 // It is the consumer's responsibility to use this class when appropriate, i.e.
  31 // only with extensions that have not-yet-loaded lazy background pages.
  32 class LazyBackgroundTaskQueue : public content::NotificationObserver {
  33  public:
  34   typedef base::Callback<void(ExtensionHost*)> PendingTask;
  35
  36   explicit LazyBackgroundTaskQueue(content::BrowserContext* browser_context);
  37   virtual ~LazyBackgroundTaskQueue();
  38
  39   // Returns the number of extensions having pending tasks.
  40   size_t extensions_with_pending_tasks() { return pending_tasks_.size(); }
  41
  42   // Returns true if the task should be added to the queue (that is, if the
  43   // extension has a lazy background page that isn't ready yet). If the
  44   // extension has a lazy background page that is being suspended this method
  45   // cancels that suspension.
  46   bool ShouldEnqueueTask(content::BrowserContext* context,
  47                          const Extension* extension);
  48
  49   // Adds a task to the queue for a given extension. If this is the first
  50   // task added for the extension, its lazy background page will be loaded.
  51   // The task will be called either when the page is loaded, or when the
  52   // page fails to load for some reason (e.g. a crash or browser
  53   // shutdown). In the latter case, the ExtensionHost parameter is NULL.
  54   void AddPendingTask(
  55       content::BrowserContext* context,
  56       const std::string& extension_id,
  57       const PendingTask& task);
  58
  59  private:
  60   FRIEND_TEST_ALL_PREFIXES(LazyBackgroundTaskQueueTest, ProcessPendingTasks);
  61
  62   // A map between a BrowserContext/extension_id pair and the queue of tasks
  63   // pending the load of its background page.
  64   typedef std::string ExtensionID;
  65   typedef std::pair<content::BrowserContext*, ExtensionID> PendingTasksKey;
  66   typedef std::vector<PendingTask> PendingTasksList;
  67   typedef std::map<PendingTasksKey,
  68                    linked_ptr<PendingTasksList> > PendingTasksMap;
  69
  70   // content::NotificationObserver interface.
  71   virtual void Observe(int type,
  72                        const content::NotificationSource& source,
  73                        const content::NotificationDetails& details) OVERRIDE;
  74
  75   // Called when a lazy background page has finished loading, or has failed to
  76   // load (host is NULL in that case). All enqueued tasks are run in order.
  77   void ProcessPendingTasks(
  78       ExtensionHost* host,
  79       content::BrowserContext* context,
  80       const Extension* extension);
  81
  82   content::BrowserContext* browser_context_;
  83   content::NotificationRegistrar registrar_;
  84   PendingTasksMap pending_tasks_;
  85 };
  86
  87 }  // namespace extensions
  88
  89 #endif  // EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_