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 "base/scoped_observer.h"
  16 #include "content/public/browser/notification_observer.h"
  17 #include "content/public/browser/notification_registrar.h"
  18 #include "extensions/browser/extension_registry_observer.h"
  19
  20 namespace content {
  21 class BrowserContext;
  22 }
  23
  24 namespace extensions {
  25 class Extension;
  26 class ExtensionHost;
  27 class ExtensionRegistry;
  28
  29 // This class maintains a queue of tasks that should execute when an
  30 // extension's lazy background page is loaded. It is also in charge of loading
  31 // the page when the first task is queued.
  32 //
  33 // It is the consumer's responsibility to use this class when appropriate, i.e.
  34 // only with extensions that have not-yet-loaded lazy background pages.
  35 class LazyBackgroundTaskQueue : public content::NotificationObserver,
  36                                 public ExtensionRegistryObserver {
  37  public:
  38   typedef base::Callback<void(ExtensionHost*)> PendingTask;
  39
  40   explicit LazyBackgroundTaskQueue(content::BrowserContext* browser_context);
  41   ~LazyBackgroundTaskQueue() override;
  42
  43   // Returns the number of extensions having pending tasks.
  44   size_t extensions_with_pending_tasks() { return pending_tasks_.size(); }
  45
  46   // Returns true if the task should be added to the queue (that is, if the
  47   // extension has a lazy background page that isn't ready yet). If the
  48   // extension has a lazy background page that is being suspended this method
  49   // cancels that suspension.
  50   bool ShouldEnqueueTask(content::BrowserContext* context,
  51                          const Extension* extension);
  52
  53   // Adds a task to the queue for a given extension. If this is the first
  54   // task added for the extension, its lazy background page will be loaded.
  55   // The task will be called either when the page is loaded, or when the
  56   // page fails to load for some reason (e.g. a crash or browser
  57   // shutdown). In the latter case, the ExtensionHost parameter is NULL.
  58   void AddPendingTask(
  59       content::BrowserContext* context,
  60       const std::string& extension_id,
  61       const PendingTask& task);
  62
  63  private:
  64   FRIEND_TEST_ALL_PREFIXES(LazyBackgroundTaskQueueTest, ProcessPendingTasks);
  65
  66   // A map between a BrowserContext/extension_id pair and the queue of tasks
  67   // pending the load of its background page.
  68   typedef std::string ExtensionID;
  69   typedef std::pair<content::BrowserContext*, ExtensionID> PendingTasksKey;
  70   typedef std::vector<PendingTask> PendingTasksList;
  71   typedef std::map<PendingTasksKey,
  72                    linked_ptr<PendingTasksList> > PendingTasksMap;
  73
  74   // content::NotificationObserver interface.
  75   void Observe(int type,
  76                const content::NotificationSource& source,
  77                const content::NotificationDetails& details) override;
  78
  79   // ExtensionRegistryObserver interface.
  80   void OnExtensionUnloaded(content::BrowserContext* browser_context,
  81                            const Extension* extension,
  82                            UnloadedExtensionInfo::Reason reason) override;
  83
  84   // Called when a lazy background page has finished loading, or has failed to
  85   // load (host is NULL in that case). All enqueued tasks are run in order.
  86   void ProcessPendingTasks(
  87       ExtensionHost* host,
  88       content::BrowserContext* context,
  89       const Extension* extension);
  90
  91   content::BrowserContext* browser_context_;
  92   content::NotificationRegistrar registrar_;
  93   PendingTasksMap pending_tasks_;
  94
  95   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
  96       extension_registry_observer_;
  97 };
  98
  99 }  // namespace extensions
 100
 101 #endif  // EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_