Implement fetching, caching and retrieval of external policy data

chrome/browser/policy/cloud/cloud_external_data_manager_base.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_POLICY_CLOUD_CLOUD_EXTERNAL_DATA_MANAGER_BASE_H_
+#define CHROME_BROWSER_POLICY_CLOUD_CLOUD_EXTERNAL_DATA_MANAGER_BASE_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/policy/cloud/cloud_external_data_manager.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace policy {
+
+class CloudExternalDataStore;
+struct PolicyDefinitionList;
+
+// Downloads, verifies, caches and retrieves external data referenced by
+// policies.
+// This is a common base class used by specializations for regular users and
+// device-local accounts.
+class CloudExternalDataManagerBase : public CloudExternalDataManager {
+ public:
+  // The |policy_definitions| are used to determine the maximum size that the
+  // data referenced by each policy can have. All data download, verification,
+  // caching and retrieval tasks are run via the |backend_task_runner|.
+  CloudExternalDataManagerBase(
+      const PolicyDefinitionList* policy_definitions,
+      scoped_refptr<base::SequencedTaskRunner> backend_task_runner);
+  virtual ~CloudExternalDataManagerBase();
+
+  // Allows downloaded external data to be cached in |external_data_store|.
+  // Ownership of the store is taken. The store can be destroyed by calling
+  // SetExternalDataStore(scoped_ptr<CloudExternalDataStore>()). Accesses to the
+  // store are made via |backend_task_runner_| only.
+  void SetExternalDataStore(
+      scoped_ptr<CloudExternalDataStore> external_data_store);
+
+  // CloudExternalDataManager:
+  virtual void SetPolicyStore(CloudPolicyStore* policy_store) OVERRIDE;
+  virtual void OnPolicyStoreLoaded() OVERRIDE;
+  virtual void Connect(
+      scoped_refptr<net::URLRequestContextGetter> request_context) OVERRIDE;
+  virtual void Disconnect() OVERRIDE;
+  virtual void Fetch(
+      const std::string& policy,
+      const ExternalDataFetcher::FetchCallback& callback) OVERRIDE;
+
+ protected:
+  friend class CouldExternalDataManagerBaseTest;
+
+  // Try to download and cache all external data referenced by policies in
+  // |policy_store_|.
+  void FetchAll();
+
+  scoped_refptr<base::SequencedTaskRunner> backend_task_runner_;
+
+ private:
+  // The |backend_| handles all data download, verification, caching and
+  // retrieval. It is instantiated on the UI thread but from then on, is
+  // accessed via the |backend_task_runner_| only.
+  class Backend;
+  Backend* backend_;
+
+  DISALLOW_COPY_AND_ASSIGN(CloudExternalDataManagerBase);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_CLOUD_CLOUD_EXTERNAL_DATA_MANAGER_BASE_H_