Cache force-installed apps/extensions in device-local accounts

chrome/browser/chromeos/extensions/device_local_account_external_policy_loader.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_EXTENSIONS_DEVICE_LOCAL_ACCOUNT_EXTERNAL_POLICY_LOADER_H_
+#define CHROME_BROWSER_CHROMEOS_EXTENSIONS_DEVICE_LOCAL_ACCOUNT_EXTERNAL_POLICY_LOADER_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/compiler_specific.h"
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/sequenced_task_runner.h"
+#include "chrome/browser/chromeos/extensions/external_cache.h"
+#include "chrome/browser/extensions/external_loader.h"
+#include "chrome/browser/policy/cloud/cloud_policy_store.h"
+
+namespace chromeos {
+
+// A specialization of the ExternalLoader that serves external extensions from
+// the enterprise policy force-install list. This class is used for device-local
+// accounts in place of the ExternalPolicyLoader. The difference is that while
+// the ExternalPolicyLoader requires extensions to be downloaded on-the-fly,
+// this class caches them, allowing for offline installation.
+class DeviceLocalAccountExternalPolicyLoader
+    : public extensions::ExternalLoader,
+      public policy::CloudPolicyStore::Observer,
+      public ExternalCache::Delegate {
+ public:
+  // The list of force-installed extensions will be read from |store| and the
+  // extensions will be cached in the |cache_dir_|.
+  DeviceLocalAccountExternalPolicyLoader(policy::CloudPolicyStore* store,
+                                         const base::FilePath& cache_dir);
+  // If the cache was started, it must be stopped before |this| is destroyed.
+  virtual ~DeviceLocalAccountExternalPolicyLoader();
+
+  // While running, the cache requires exclusive write access to the
+  // |cache_dir_|.
+  bool IsCacheRunning() const;
+
+  // Start the cache. This method must only be invoked when there are no pending
+  // write operations to |cache_dir_| on any thread and none will be initiated
+  // while the cache is running.
+  void StartCache(
+      const scoped_refptr<base::SequencedTaskRunner>& cache_task_runner);
+
+  // Stop the cache. The |callback| will be invoked when the cache has shut down
+  // completely and write access to the |cache_dir_| is permitted again.
+  void StopCache(const base::Closure& callback);
+
+  // extensions::ExternalLoader:
+  virtual void StartLoading() OVERRIDE;
+
+  // policy::CloudPolicyStore::Observer:
+  virtual void OnStoreLoaded(policy::CloudPolicyStore* store) OVERRIDE;
+  virtual void OnStoreError(policy::CloudPolicyStore* store) OVERRIDE;
+
+  // ExternalCache::Delegate:
+  virtual void OnExtensionListsUpdated(
+      const base::DictionaryValue* prefs) OVERRIDE;
+
+ private:
+  // Pass the current list of force-installed extensions from the |store_| to
+  // the |external_cache_|.
+  void UpdateExtensionListFromStore();
+
+  policy::CloudPolicyStore* store_;  // Not owned.

[Joao da Silva, 2013/10/17 14:57:54]

I find this comment pattern quite low value and just adding noise. If it were
owned it'd be in a scoped_ptr.

If it were owned and not in a scoped_ptr (because it's posted to a DeleteSoon on
another thread, or something) then it would warrant an ownership comment.

wdyt?

[bartfab (slow), 2013/10/18 12:58:39]

A matter of opinion - some reviewers explicitly ask for this, others discourage
it. Removed.

+  const base::FilePath cache_dir_;
+  scoped_ptr<ExternalCache> external_cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceLocalAccountExternalPolicyLoader);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_DEVICE_LOCAL_ACCOUNT_EXTERNAL_POLICY_LOADER_H_