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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // TransientDeviceIds keep track of transient IDs for removable devices, so
      6 // persistent device IDs are not exposed to renderers. Once a removable device
      7 // gets mapped to a transient ID, the mapping remains valid for the duration of
      8 // TransientDeviceIds' lifetime.
      9 
     10 #ifndef CHROME_BROWSER_STORAGE_MONITOR_TRANSIENT_DEVICE_IDS_H_
     11 #define CHROME_BROWSER_STORAGE_MONITOR_TRANSIENT_DEVICE_IDS_H_
     12 
     13 #include <map>
     14 #include <string>
     15 
     16 #include "base/basictypes.h"
     17 #include "base/threading/thread_checker.h"
     18 
     19 class TransientDeviceIds {
     20  public:
     21   TransientDeviceIds();
     22   ~TransientDeviceIds();
     23 
     24   // Returns the transient ID for a given |device_id|.
     25   // |device_id| must be for a fixed or removable storage device.
     26   // If |device_id| has never been seen before, a new, unique transient id will
     27   // be assigned.
     28   std::string GetTransientIdForDeviceId(const std::string& device_id);
     29 
     30   // Get the reverse mapping for a transient ID. Returns an empty string if the
     31   // |transient_id| cannot be found.
     32   std::string DeviceIdFromTransientId(const std::string& transient_id) const;
     33 
     34  private:
     35   typedef std::map<std::string, std::string> IdMap;
     36 
     37   IdMap device_id_map_;
     38   IdMap transient_id_map_;
     39 
     40   base::ThreadChecker thread_checker_;
     41 
     42   DISALLOW_COPY_AND_ASSIGN(TransientDeviceIds);
     43 };
     44 
     45 #endif  // CHROME_BROWSER_STORAGE_MONITOR_TRANSIENT_DEVICE_IDS_H_
     46