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      1 // Copyright (c) 2011 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 #ifndef CHROME_COMMON_PERSISTENT_PREF_STORE_H_
      6 #define CHROME_COMMON_PERSISTENT_PREF_STORE_H_
      7 #pragma once
      8 
      9 #include <string>
     10 
     11 #include <chrome/common/pref_store.h>
     12 
     13 // This interface is complementary to the PrefStore interface, declaring
     14 // additional functionality that adds support for setting values and persisting
     15 // the data to some backing store.
     16 class PersistentPrefStore : public PrefStore {
     17  public:
     18   virtual ~PersistentPrefStore() {}
     19 
     20   // Unique integer code for each type of error so we can report them
     21   // distinctly in a histogram.
     22   // NOTE: Don't change the order here as it will change the server's meaning
     23   // of the histogram.
     24   enum PrefReadError {
     25     PREF_READ_ERROR_NONE = 0,
     26     PREF_READ_ERROR_JSON_PARSE,
     27     PREF_READ_ERROR_JSON_TYPE,
     28     PREF_READ_ERROR_ACCESS_DENIED,
     29     PREF_READ_ERROR_FILE_OTHER,
     30     PREF_READ_ERROR_FILE_LOCKED,
     31     PREF_READ_ERROR_NO_FILE,
     32     PREF_READ_ERROR_JSON_REPEAT,
     33     PREF_READ_ERROR_OTHER,
     34     PREF_READ_ERROR_FILE_NOT_SPECIFIED
     35   };
     36 
     37   // Equivalent to PrefStore::GetValue but returns a mutable value.
     38   virtual ReadResult GetMutableValue(const std::string& key,
     39                                      Value** result) = 0;
     40 
     41   // Triggers a value changed notification. This function needs to be called
     42   // if one retrieves a list or dictionary with GetMutableValue and change its
     43   // value. SetValue takes care of notifications itself. Note that
     44   // ReportValueChanged will trigger notifications even if nothing has changed.
     45   virtual void ReportValueChanged(const std::string& key) = 0;
     46 
     47   // Sets a |value| for |key| in the store. Assumes ownership of |value|, which
     48   // must be non-NULL.
     49   virtual void SetValue(const std::string& key, Value* value) = 0;
     50 
     51   // Same as SetValue, but doesn't generate notifications. This is used by
     52   // PrefService::GetMutableUserPref() in order to put empty entries
     53   // into the user pref store. Using SetValue is not an option since existing
     54   // tests rely on the number of notifications generated.
     55   virtual void SetValueSilently(const std::string& key, Value* value) = 0;
     56 
     57   // Removes the value for |key|.
     58   virtual void RemoveValue(const std::string& key) = 0;
     59 
     60   // Whether the store is in a pseudo-read-only mode where changes are not
     61   // actually persisted to disk.  This happens in some cases when there are
     62   // read errors during startup.
     63   virtual bool ReadOnly() const = 0;
     64 
     65   // Reads the preferences from disk.
     66   virtual PrefReadError ReadPrefs() = 0;
     67 
     68   // Writes the preferences to disk immediately.
     69   virtual bool WritePrefs() = 0;
     70 
     71   // Schedules an asynchronous write operation.
     72   virtual void ScheduleWritePrefs() = 0;
     73 
     74   // Lands any pending writes to disk.
     75   virtual void CommitPendingWrite() = 0;
     76 };
     77 
     78 #endif  // CHROME_COMMON_PERSISTENT_PREF_STORE_H_
     79