Move base/prefs to components/prefs

base/prefs/pref_service.h

 // Copyright (c) 2012 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.
 
-// This provides a way to access the application's current preferences.
-
-// Chromium settings and storage represent user-selected preferences and
-// information and MUST not be extracted, overwritten or modified except
-// through Chromium defined APIs.
-
-#ifndef BASE_PREFS_PREF_SERVICE_H_
-#define BASE_PREFS_PREF_SERVICE_H_
-
-#include <stdint.h>
-
-#include <set>
-#include <string>
-
-#include "base/callback.h"
-#include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/observer_list.h"
-#include "base/prefs/base_prefs_export.h"
-#include "base/prefs/persistent_pref_store.h"
-#include "base/threading/non_thread_safe.h"
-#include "base/values.h"
-
-class PrefNotifier;
-class PrefNotifierImpl;
-class PrefObserver;
-class PrefRegistry;
-class PrefValueStore;
-class PrefStore;
-
-namespace base {
-class FilePath;
-}
-
-namespace subtle {
-class PrefMemberBase;
-class ScopedUserPrefUpdateBase;
-}
-
-// Base class for PrefServices. You can use the base class to read and
-// interact with preferences, but not to register new preferences; for
-// that see e.g. PrefRegistrySimple.
-//
-// Settings and storage accessed through this class represent
-// user-selected preferences and information and MUST not be
-// extracted, overwritten or modified except through the defined APIs.
-class BASE_PREFS_EXPORT PrefService : public base::NonThreadSafe {
- public:
-  enum PrefInitializationStatus {
-    INITIALIZATION_STATUS_WAITING,
-    INITIALIZATION_STATUS_SUCCESS,
-    INITIALIZATION_STATUS_CREATED_NEW_PREF_STORE,
-    INITIALIZATION_STATUS_ERROR
-  };
-
-  // A helper class to store all the information associated with a preference.
-  class BASE_PREFS_EXPORT Preference {
-   public:
-    // The type of the preference is determined by the type with which it is
-    // registered. This type needs to be a boolean, integer, double, string,
-    // dictionary (a branch), or list.  You shouldn't need to construct this on
-    // your own; use the PrefService::Register*Pref methods instead.
-    Preference(const PrefService* service,
-               const std::string& name,
-               base::Value::Type type);
-    ~Preference() {}
-
-    // Returns the name of the Preference (i.e., the key, e.g.,
-    // browser.window_placement).
-    const std::string name() const;
-
-    // Returns the registered type of the preference.
-    base::Value::Type GetType() const;
-
-    // Returns the value of the Preference, falling back to the registered
-    // default value if no other has been set.
-    const base::Value* GetValue() const;
-
-    // Returns the value recommended by the admin, if any.
-    const base::Value* GetRecommendedValue() const;
-
-    // Returns true if the Preference is managed, i.e. set by an admin policy.
-    // Since managed prefs have the highest priority, this also indicates
-    // whether the pref is actually being controlled by the policy setting.
-    bool IsManaged() const;
-
-    // Returns true if the Preference is controlled by the custodian of the
-    // supervised user. Since a supervised user is not expected to have an admin
-    // policy, this is the controlling pref if set.
-    bool IsManagedByCustodian() const;
-
-    // Returns true if the Preference is recommended, i.e. set by an admin
-    // policy but the user is allowed to change it.
-    bool IsRecommended() const;
-
-    // Returns true if the Preference has a value set by an extension, even if
-    // that value is being overridden by a higher-priority source.
-    bool HasExtensionSetting() const;
-
-    // Returns true if the Preference has a user setting, even if that value is
-    // being overridden by a higher-priority source.
-    bool HasUserSetting() const;
-
-    // Returns true if the Preference value is currently being controlled by an
-    // extension, and not by any higher-priority source.
-    bool IsExtensionControlled() const;
-
-    // Returns true if the Preference value is currently being controlled by a
-    // user setting, and not by any higher-priority source.
-    bool IsUserControlled() const;
-
-    // Returns true if the Preference is currently using its default value,
-    // and has not been set by any higher-priority source (even with the same
-    // value).
-    bool IsDefaultValue() const;
-
-    // Returns true if the user can change the Preference value, which is the
-    // case if no higher-priority source than the user store controls the
-    // Preference.
-    bool IsUserModifiable() const;
-
-    // Returns true if an extension can change the Preference value, which is
-    // the case if no higher-priority source than the extension store controls
-    // the Preference.
-    bool IsExtensionModifiable() const;
-
-    // Return the registration flags for this pref as a bitmask of
-    // PrefRegistry::PrefRegistrationFlags.
-    uint32_t registration_flags() const { return registration_flags_; }
-
-   private:
-    friend class PrefService;
-
-    PrefValueStore* pref_value_store() const {
-      return pref_service_->pref_value_store_.get();
-    }
-
-    const std::string name_;
-
-    const base::Value::Type type_;
-
-    uint32_t registration_flags_;
-
-    // Reference to the PrefService in which this pref was created.
-    const PrefService* pref_service_;
-  };
-
-  // You may wish to use PrefServiceFactory or one of its subclasses
-  // for simplified construction.
-  PrefService(
-      PrefNotifierImpl* pref_notifier,
-      PrefValueStore* pref_value_store,
-      PersistentPrefStore* user_prefs,
-      PrefRegistry* pref_registry,
-      base::Callback<void(PersistentPrefStore::PrefReadError)>
-          read_error_callback,
-      bool async);
-  virtual ~PrefService();
-
-  // Lands pending writes to disk. This should only be used if we need to save
-  // immediately (basically, during shutdown).
-  void CommitPendingWrite();
-
-  // Schedule a write if there is any lossy data pending. Unlike
-  // CommitPendingWrite() this does not immediately sync to disk, instead it
-  // triggers an eventual write if there is lossy data pending and if there
-  // isn't one scheduled already.
-  void SchedulePendingLossyWrites();
-
-  // Returns true if the preference for the given preference name is available
-  // and is managed.
-  bool IsManagedPreference(const std::string& pref_name) const;
-
-  // Returns true if the preference for the given preference name is available
-  // and is controlled by the parent/guardian of the child Account.
-  bool IsPreferenceManagedByCustodian(const std::string& pref_name) const;
-
-  // Returns |true| if a preference with the given name is available and its
-  // value can be changed by the user.
-  bool IsUserModifiablePreference(const std::string& pref_name) const;
-
-  // Look up a preference.  Returns NULL if the preference is not
-  // registered.
-  const PrefService::Preference* FindPreference(const std::string& path) const;
-
-  // If the path is valid and the value at the end of the path matches the type
-  // specified, it will return the specified value.  Otherwise, the default
-  // value (set when the pref was registered) will be returned.
-  bool GetBoolean(const std::string& path) const;
-  int GetInteger(const std::string& path) const;
-  double GetDouble(const std::string& path) const;
-  std::string GetString(const std::string& path) const;
-  base::FilePath GetFilePath(const std::string& path) const;
-
-  // Returns the branch if it exists, or the registered default value otherwise.
-  // Note that |path| must point to a registered preference. In that case, these
-  // functions will never return NULL.
-  const base::DictionaryValue* GetDictionary(const std::string& path) const;
-  const base::ListValue* GetList(const std::string& path) const;
-
-  // Removes a user pref and restores the pref to its default value.
-  void ClearPref(const std::string& path);
-
-  // If the path is valid (i.e., registered), update the pref value in the user
-  // prefs.
-  // To set the value of dictionary or list values in the pref tree use
-  // Set(), but to modify the value of a dictionary or list use either
-  // ListPrefUpdate or DictionaryPrefUpdate from scoped_user_pref_update.h.
-  void Set(const std::string& path, const base::Value& value);
-  void SetBoolean(const std::string& path, bool value);
-  void SetInteger(const std::string& path, int value);
-  void SetDouble(const std::string& path, double value);
-  void SetString(const std::string& path, const std::string& value);
-  void SetFilePath(const std::string& path, const base::FilePath& value);
-
-  // Int64 helper methods that actually store the given value as a string.
-  // Note that if obtaining the named value via GetDictionary or GetList, the
-  // Value type will be TYPE_STRING.
-  void SetInt64(const std::string& path, int64_t value);
-  int64_t GetInt64(const std::string& path) const;
-
-  // As above, but for unsigned values.
-  void SetUint64(const std::string& path, uint64_t value);
-  uint64_t GetUint64(const std::string& path) const;
-
-  // Returns the value of the given preference, from the user pref store. If
-  // the preference is not set in the user pref store, returns NULL.
-  const base::Value* GetUserPrefValue(const std::string& path) const;
-
-  // Changes the default value for a preference. Takes ownership of |value|.
-  //
-  // Will cause a pref change notification to be fired if this causes
-  // the effective value to change.
-  void SetDefaultPrefValue(const std::string& path, base::Value* value);
-
-  // Returns the default value of the given preference. |path| must point to a
-  // registered preference. In that case, will never return NULL.
-  const base::Value* GetDefaultPrefValue(const std::string& path) const;
-
-  // Returns true if a value has been set for the specified path.
-  // NOTE: this is NOT the same as FindPreference. In particular
-  // FindPreference returns whether RegisterXXX has been invoked, where as
-  // this checks if a value exists for the path.
-  bool HasPrefPath(const std::string& path) const;
-
-  // Returns a dictionary with effective preference values.
-  scoped_ptr<base::DictionaryValue> GetPreferenceValues() const;
-
-  // Returns a dictionary with effective preference values, omitting prefs that
-  // are at their default values.
-  scoped_ptr<base::DictionaryValue> GetPreferenceValuesOmitDefaults() const;
-
-  // Returns a dictionary with effective preference values. Contrary to
-  // GetPreferenceValues(), the paths of registered preferences are not split on
-  // '.' characters. If a registered preference stores a dictionary, however,
-  // the hierarchical structure inside the preference will be preserved.
-  // For example, if "foo.bar" is a registered preference, the result could look
-  // like this:
-  //   {"foo.bar": {"a": {"b": true}}}.
-  scoped_ptr<base::DictionaryValue> GetPreferenceValuesWithoutPathExpansion()
-      const;
-
-  bool ReadOnly() const;
-
-  PrefInitializationStatus GetInitializationStatus() const;
-
-  // Tell our PrefValueStore to update itself to |command_line_store|.
-  // Takes ownership of the store.
-  virtual void UpdateCommandLinePrefStore(PrefStore* command_line_store);
-
-  // We run the callback once, when initialization completes. The bool
-  // parameter will be set to true for successful initialization,
-  // false for unsuccessful.
-  void AddPrefInitObserver(base::Callback<void(bool)> callback);
-
-  // Returns the PrefRegistry object for this service. You should not
-  // use this; the intent is for no registrations to take place after
-  // PrefService has been constructed.
-  //
-  // Instead of using this method, the recommended approach is to
-  // register all preferences for a class Xyz up front in a static
-  // Xyz::RegisterPrefs function, which gets invoked early in the
-  // application's start-up, before a PrefService is created.
-  //
-  // As an example, prefs registration in Chrome is triggered by the
-  // functions chrome::RegisterPrefs (for global preferences) and
-  // chrome::RegisterProfilePrefs (for user-specific preferences)
-  // implemented in chrome/browser/prefs/browser_prefs.cc.
-  PrefRegistry* DeprecatedGetPrefRegistry();
-
- protected:
-  // The PrefNotifier handles registering and notifying preference observers.
-  // It is created and owned by this PrefService. Subclasses may access it for
-  // unit testing.
-  scoped_ptr<PrefNotifierImpl> pref_notifier_;
-
-  // The PrefValueStore provides prioritized preference values. It is owned by
-  // this PrefService. Subclasses may access it for unit testing.
-  scoped_ptr<PrefValueStore> pref_value_store_;
-
-  scoped_refptr<PrefRegistry> pref_registry_;
-
-  // Pref Stores and profile that we passed to the PrefValueStore.
-  scoped_refptr<PersistentPrefStore> user_pref_store_;
-
-  // Callback to call when a read error occurs.
-  base::Callback<void(PersistentPrefStore::PrefReadError)> read_error_callback_;
-
- private:
-  // Hash map expected to be fastest here since it minimises expensive
-  // string comparisons. Order is unimportant, and deletions are rare.
-  // Confirmed on Android where this speeded Chrome startup by roughly 50ms
-  // vs. std::map, and by roughly 180ms vs. std::set of Preference pointers.
-  typedef base::hash_map<std::string, Preference> PreferenceMap;
-
-  // Give access to ReportUserPrefChanged() and GetMutableUserPref().
-  friend class subtle::ScopedUserPrefUpdateBase;
-  friend class PrefServiceTest_WriteablePrefStoreFlags_Test;
-
-  // Registration of pref change observers must be done using the
-  // PrefChangeRegistrar, which is declared as a friend here to grant it
-  // access to the otherwise protected members Add/RemovePrefObserver.
-  // PrefMember registers for preferences changes notification directly to
-  // avoid the storage overhead of the registrar, so its base class must be
-  // declared as a friend, too.
-  friend class PrefChangeRegistrar;
-  friend class subtle::PrefMemberBase;
-
-  // These are protected so they can only be accessed by the friend
-  // classes listed above.
-  //
-  // If the pref at the given path changes, we call the observer's
-  // OnPreferenceChanged method. Note that observers should not call
-  // these methods directly but rather use a PrefChangeRegistrar to
-  // make sure the observer gets cleaned up properly.
-  //
-  // Virtual for testing.
-  virtual void AddPrefObserver(const std::string& path, PrefObserver* obs);
-  virtual void RemovePrefObserver(const std::string& path, PrefObserver* obs);
-
-  // Sends notification of a changed preference. This needs to be called by
-  // a ScopedUserPrefUpdate if a DictionaryValue or ListValue is changed.
-  void ReportUserPrefChanged(const std::string& key);
-
-  // Sets the value for this pref path in the user pref store and informs the
-  // PrefNotifier of the change.
-  void SetUserPrefValue(const std::string& path, base::Value* new_value);
-
-  // Load preferences from storage, attempting to diagnose and handle errors.
-  // This should only be called from the constructor.
-  void InitFromStorage(bool async);
-
-  // Used to set the value of dictionary or list values in the user pref store.
-  // This will create a dictionary or list if one does not exist in the user
-  // pref store. This method returns NULL only if you're requesting an
-  // unregistered pref or a non-dict/non-list pref.
-  // |type| may only be Values::TYPE_DICTIONARY or Values::TYPE_LIST and
-  // |path| must point to a registered preference of type |type|.
-  // Ownership of the returned value remains at the user pref store.
-  base::Value* GetMutableUserPref(const std::string& path,
-                                  base::Value::Type type);
-
-  // GetPreferenceValue is the equivalent of FindPreference(path)->GetValue(),
-  // it has been added for performance. If is faster because it does
-  // not need to find or create a Preference object to get the
-  // value (GetValue() calls back though the preference service to
-  // actually get the value.).
-  const base::Value* GetPreferenceValue(const std::string& path) const;
-
-  // Local cache of registered Preference objects. The pref_registry_
-  // is authoritative with respect to what the types and default values
-  // of registered preferences are.
-  mutable PreferenceMap prefs_map_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrefService);
-};
-
-#endif  // BASE_PREFS_PREF_SERVICE_H_
+// TODO(brettw) remove this forwarding header when prefs is completely moved to
+// components.
+#include "components/prefs/pref_service.h"