Support policies referencing external data for device-local accounts

chrome/browser/chromeos/policy/device_local_account_external_data_manager.h

+// 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 CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_LOCAL_ACCOUNT_EXTERNAL_DATA_MANAGER_H_
+#define CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_LOCAL_ACCOUNT_EXTERNAL_DATA_MANAGER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/browser/chromeos/policy/cloud_external_data_manager_base.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace policy {
+
+struct PolicyDefinitionList;
+class ResourceCache;
+
+// Downloads, verifies, caches and retrieves external data referenced by
+// policies.
+// This is the implementation for device-local accounts on Chrome OS.
+// The manager is created by the DeviceLocalAccountExternalDataService and must
+// not outlive it because the |resource_cache| is owned by the service. However,
+// the service is not the manager's sole owner: The manager lives as long as
+// either the service or a DeviceLocalAccountPolicyProvider references it. This
+// is necessary because a device-local account can be removed from policy (thus
+// removing it from the service) while a session is in progress and a provider
+// exists for the account. The manager is only destroyed when neither service
+// nor provider reference it anymore.
+class DeviceLocalAccountExternalDataManager
+    : public CloudExternalDataManagerBase,
+      public base::RefCounted<DeviceLocalAccountExternalDataManager> {
+ private:
+  friend class DeviceLocalAccountExternalDataService;
+  friend class base::RefCounted<DeviceLocalAccountExternalDataManager>;
+
+  // The |policy_definitions| are used to determine the maximum size that the
+  // data referenced by each policy can have. Download scheduling, verification,
+  // caching and retrieval tasks are done via the |backend_task_runner|, which
+  // must support file I/O. Network I/O is done via the |io_task_runner|. The
+  // manager is responsible for external data references by policies in
+  // |policy_store|. Downloaded external data is stored in the |resource_cache|.
+  // The data is keyed by |account_id|, allowing one cache to be shared by any
+  // number of accounts. To ensure synchronization of operations on the shared
+  // cache, all its users must access the cache via |backend_task_runner| only.
+  DeviceLocalAccountExternalDataManager(
+      const std::string& account_id,
+      const PolicyDefinitionList* policy_definitions,
+      scoped_refptr<base::SequencedTaskRunner> backend_task_runner,
+      scoped_refptr<base::SequencedTaskRunner> io_task_runner,
+      ResourceCache* resource_cache);
+  virtual ~DeviceLocalAccountExternalDataManager();
+
+  // CloudExternalDataManagerBase:
+  virtual void OnPolicyStoreLoaded() OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceLocalAccountExternalDataManager);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_CHROMEOS_POLICY_DEVICE_LOCAL_ACCOUNT_EXTERNAL_DATA_MANAGER_H_