Move policy code into components/policy.

chrome/browser/policy/cloud/external_policy_data_updater.h

-// Copyright (c) 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_EXTERNAL_POLICY_DATA_UPDATER_H_
-#define CHROME_BROWSER_POLICY_CLOUD_EXTERNAL_POLICY_DATA_UPDATER_H_
-
-#include <map>
-#include <queue>
-#include <string>
-
-#include "base/basictypes.h"
-#include "base/callback_forward.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-
-namespace base {
-class SequencedTaskRunner;
-}
-
-namespace policy {
-
-class ExternalPolicyDataFetcher;
-
-// This class downloads external policy data. Given a |Request|, data is fetched
-// from the |url|, verified to not exceed |max_size| and to match the expected
-// |hash| and then handed to a callback that can do further verification before
-// finally deciding whether the fetched data is valid.
-// If a fetch is not successful or retrieves invalid data, retries are scheduled
-// with exponential backoff.
-// The actual fetching is handled by an ExternalPolicyDataFetcher, allowing this
-// class to run on a background thread where network I/O is not possible.
-class ExternalPolicyDataUpdater {
- public:
-  struct Request {
-   public:
-    Request();
-    Request(const std::string& url, const std::string& hash, int64 max_size);
-
-    bool operator==(const Request& other) const;
-
-    std::string url;
-    std::string hash;
-    int64 max_size;
-  };
-
-  // This callback is invoked when a fetch has successfully retrieved |data|
-  // that does not exceed |max_size| and matches the expected |hash|. The
-  // callback can do further verification to decide whether the fetched data is
-  // valid.
-  // If the callback returns |true|, the data is accepted and the |Request| is
-  // finished. If the callback returns |false|, the data is rejected and the
-  // fetch is retried after a long backoff. Note that in this case, the callback
-  // may be invoked multiple times as the fetch is repeated. Make sure to not
-  // bind base::Passed() scoped_ptrs to the callback in such cases as these
-  // become invalid after a callback has been run once. base::Owned() can be
-  // used in all cases.
-  typedef base::Callback<bool(const std::string&)> FetchSuccessCallback;
-
-  // This class runs on the background thread represented by |task_runner|,
-  // which must support file I/O. All network I/O is forwarded to a different
-  // thread by the |external_policy_data_fetcher|.
-  ExternalPolicyDataUpdater(
-      scoped_refptr<base::SequencedTaskRunner> task_runner,
-      scoped_ptr<ExternalPolicyDataFetcher> external_policy_data_fetcher,
-      size_t max_parallel_fetches);
-  ~ExternalPolicyDataUpdater();
-
-  // Fetches the external data specified in the |request|. The |key| is an
-  // opaque identifier. If another request for the same |key| is still pending,
-  // it will be canceled and replaced with the new |request|. The callback will
-  // be invoked after a successful fetch. See the documentation of
-  // |FetchSuccessCallback| for more details.
-  void FetchExternalData(const std::string key,
-                         const Request& request,
-                         const FetchSuccessCallback& callback);
-
-  // Cancels the pending request identified by |key|. If no such request is
-  // pending, does nothing.
-  void CancelExternalDataFetch(const std::string& key);
-
- private:
-  class FetchJob;
-
-  // Starts jobs from the |job_queue_| until |max_parallel_jobs_| are running or
-  // the queue is depleted.
-  void StartNextJobs();
-
-  // Appends |job| to the |job_queue_| and starts it immediately if less than
-  // |max_parallel_jobs_| are running.
-  void ScheduleJob(FetchJob* job);
-
-  // Callback for jobs that succeeded.
-  void OnJobSucceeded(FetchJob* job);
-
-  // Callback for jobs that failed.
-  void OnJobFailed(FetchJob* job);
-
-  scoped_refptr<base::SequencedTaskRunner> task_runner_;
-  scoped_ptr<ExternalPolicyDataFetcher> external_policy_data_fetcher_;
-
-  // The maximum number of jobs to run in parallel.
-  size_t max_parallel_jobs_;
-
-  // The number of jobs currently running.
-  size_t running_jobs_;
-
-  // Queue of jobs waiting to be run. Jobs are taken off the queue and started
-  // by StartNextJobs().
-  std::queue<base::WeakPtr<FetchJob> > job_queue_;
-
-  // Map that owns all existing jobs, regardless of whether they are currently
-  // queued, running or waiting for a retry.
-  std::map<std::string, FetchJob*> job_map_;
-
-  // |True| once the destructor starts. Prevents jobs from being started during
-  // shutdown.
-  bool shutting_down_;
-
-  DISALLOW_COPY_AND_ASSIGN(ExternalPolicyDataUpdater);
-};
-
-}  // namespace policy
-
-#endif  // CHROME_BROWSER_POLICY_CLOUD_EXTERNAL_POLICY_DATA_UPDATER_H_