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// Copyright 2013 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 EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_
#define EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_
#include <stddef.h>
#include <map>
#include <string>
#include "base/callback_forward.h"
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/memory/linked_ptr.h"
#include "base/scoped_observer.h"
#include "components/keyed_service/core/keyed_service.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
#include "extensions/browser/extension_registry_observer.h"
namespace content {
class BrowserContext;
}
namespace extensions {
class Extension;
class ExtensionHost;
class ExtensionRegistry;
// 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 KeyedService,
public content::NotificationObserver,
public ExtensionRegistryObserver {
public:
typedef base::Callback<void(ExtensionHost*)> PendingTask;
explicit LazyBackgroundTaskQueue(content::BrowserContext* browser_context);
~LazyBackgroundTaskQueue() override;
// Convenience method to return the LazyBackgroundTaskQueue for a given
// |context|.
static LazyBackgroundTaskQueue* Get(content::BrowserContext* context);
// Returns the number of extensions having pending tasks.
size_t extensions_with_pending_tasks() { return pending_tasks_.size(); }
// 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). If the
// extension has a lazy background page that is being suspended this method
// cancels that suspension.
bool ShouldEnqueueTask(content::BrowserContext* context,
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 or browser
// shutdown). In the latter case, the ExtensionHost parameter is NULL.
void AddPendingTask(
content::BrowserContext* context,
const std::string& extension_id,
const PendingTask& task);
private:
FRIEND_TEST_ALL_PREFIXES(LazyBackgroundTaskQueueTest, ProcessPendingTasks);
// A map between a BrowserContext/extension_id pair and the queue of tasks
// pending the load of its background page.
typedef std::string ExtensionID;
typedef std::pair<content::BrowserContext*, ExtensionID> PendingTasksKey;
typedef std::vector<PendingTask> PendingTasksList;
typedef std::map<PendingTasksKey,
linked_ptr<PendingTasksList> > PendingTasksMap;
// content::NotificationObserver interface.
void Observe(int type,
const content::NotificationSource& source,
const content::NotificationDetails& details) override;
// ExtensionRegistryObserver interface.
void OnExtensionUnloaded(content::BrowserContext* browser_context,
const Extension* extension,
UnloadedExtensionInfo::Reason reason) 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,
content::BrowserContext* context,
const Extension* extension);
content::BrowserContext* browser_context_;
content::NotificationRegistrar registrar_;
PendingTasksMap pending_tasks_;
ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
extension_registry_observer_;
};
} // namespace extensions
#endif // EXTENSIONS_BROWSER_LAZY_BACKGROUND_TASK_QUEUE_H_
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