Move base/prefs to components/prefs

base/prefs/pref_value_store.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.
 
-#ifndef BASE_PREFS_PREF_VALUE_STORE_H_
-#define BASE_PREFS_PREF_VALUE_STORE_H_
-
-#include <map>
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/prefs/base_prefs_export.h"
-#include "base/prefs/pref_store.h"
-#include "base/values.h"
-
-class PrefNotifier;
-class PrefStore;
-
-// The PrefValueStore manages various sources of values for Preferences
-// (e.g., configuration policies, extensions, and user settings). It returns
-// the value of a Preference from the source with the highest priority, and
-// allows setting user-defined values for preferences that are not managed.
-//
-// Unless otherwise explicitly noted, all of the methods of this class must
-// be called on the UI thread.
-class BASE_PREFS_EXPORT PrefValueStore {
- public:
-  typedef base::Callback<void(const std::string&)> PrefChangedCallback;
-
-  // In decreasing order of precedence:
-  //   |managed_prefs| contains all preferences from mandatory policies.
-  //   |supervised_user_prefs| contains all preferences from supervised user
-  //        settings, i.e. settings configured for a supervised user by their
-  //        custodian.
-  //   |extension_prefs| contains preference values set by extensions.
-  //   |command_line_prefs| contains preference values set by command-line
-  //        switches.
-  //   |user_prefs| contains all user-set preference values.
-  //   |recommended_prefs| contains all preferences from recommended policies.
-  //   |default_prefs| contains application-default preference values. It must
-  //        be non-null if any preferences are to be registered.
-  //
-  // |pref_notifier| facilitates broadcasting preference change notifications
-  // to the world.
-  PrefValueStore(PrefStore* managed_prefs,
-                 PrefStore* supervised_user_prefs,
-                 PrefStore* extension_prefs,
-                 PrefStore* command_line_prefs,
-                 PrefStore* user_prefs,
-                 PrefStore* recommended_prefs,
-                 PrefStore* default_prefs,
-                 PrefNotifier* pref_notifier);
-  virtual ~PrefValueStore();
-
-  // Creates a clone of this PrefValueStore with PrefStores overwritten
-  // by the parameters passed, if unequal NULL.
-  PrefValueStore* CloneAndSpecialize(PrefStore* managed_prefs,
-                                     PrefStore* supervised_user_prefs,
-                                     PrefStore* extension_prefs,
-                                     PrefStore* command_line_prefs,
-                                     PrefStore* user_prefs,
-                                     PrefStore* recommended_prefs,
-                                     PrefStore* default_prefs,
-                                     PrefNotifier* pref_notifier);
-
-  // A PrefValueStore can have exactly one callback that is directly
-  // notified of preferences changing in the store. This does not
-  // filter through the PrefNotifier mechanism, which may not forward
-  // certain changes (e.g. unregistered prefs).
-  void set_callback(const PrefChangedCallback& callback);
-
-  // Gets the value for the given preference name that has the specified value
-  // type. Values stored in a PrefStore that have the matching |name| but
-  // a non-matching |type| are silently skipped. Returns true if a valid value
-  // was found in any of the available PrefStores. Most callers should use
-  // Preference::GetValue() instead of calling this method directly.
-  bool GetValue(const std::string& name,
-                base::Value::Type type,
-                const base::Value** out_value) const;
-
-  // Gets the recommended value for the given preference name that has the
-  // specified value type. A value stored in the recommended PrefStore that has
-  // the matching |name| but a non-matching |type| is silently ignored. Returns
-  // true if a valid value was found. Most callers should use
-  // Preference::GetRecommendedValue() instead of calling this method directly.
-  bool GetRecommendedValue(const std::string& name,
-                           base::Value::Type type,
-                           const base::Value** out_value) const;
-
-  // These methods return true if a preference with the given name is in the
-  // indicated pref store, even if that value is currently being overridden by
-  // a higher-priority source.
-  bool PrefValueInManagedStore(const std::string& name) const;
-  bool PrefValueInSupervisedStore(const std::string& name) const;
-  bool PrefValueInExtensionStore(const std::string& name) const;
-  bool PrefValueInUserStore(const std::string& name) const;
-
-  // These methods return true if a preference with the given name is actually
-  // being controlled by the indicated pref store and not being overridden by
-  // a higher-priority source.
-  bool PrefValueFromExtensionStore(const std::string& name) const;
-  bool PrefValueFromUserStore(const std::string& name) const;
-  bool PrefValueFromRecommendedStore(const std::string& name) const;
-  bool PrefValueFromDefaultStore(const std::string& name) const;
-
-  // Check whether a Preference value is modifiable by the user, i.e. whether
-  // there is no higher-priority source controlling it.
-  bool PrefValueUserModifiable(const std::string& name) const;
-
-  // Check whether a Preference value is modifiable by an extension, i.e.
-  // whether there is no higher-priority source controlling it.
-  bool PrefValueExtensionModifiable(const std::string& name) const;
-
-  // Update the command line PrefStore with |command_line_prefs|.
-  void UpdateCommandLinePrefStore(PrefStore* command_line_prefs);
-
- private:
-  // PrefStores must be listed here in order from highest to lowest priority.
-  //   MANAGED contains all managed preference values that are provided by
-  //      mandatory policies (e.g. Windows Group Policy or cloud policy).
-  //   SUPERVISED_USER contains preferences that are valid for supervised users.
-  //   EXTENSION contains preference values set by extensions.
-  //   COMMAND_LINE contains preference values set by command-line switches.
-  //   USER contains all user-set preference values.
-  //   RECOMMENDED contains all preferences that are provided by recommended
-  //      policies.
-  //   DEFAULT contains all application default preference values.
-  enum PrefStoreType {
-    // INVALID_STORE is not associated with an actual PrefStore but used as
-    // an invalid marker, e.g. as a return value.
-    INVALID_STORE = -1,
-    MANAGED_STORE = 0,
-    SUPERVISED_USER_STORE,
-    EXTENSION_STORE,
-    COMMAND_LINE_STORE,
-    USER_STORE,
-    RECOMMENDED_STORE,
-    DEFAULT_STORE,
-    PREF_STORE_TYPE_MAX = DEFAULT_STORE
-  };
-
-  // Keeps a PrefStore reference on behalf of the PrefValueStore and monitors
-  // the PrefStore for changes, forwarding notifications to PrefValueStore. This
-  // indirection is here for the sake of disambiguating notifications from the
-  // individual PrefStores.
-  class PrefStoreKeeper : public PrefStore::Observer {
-   public:
-    PrefStoreKeeper();
-    ~PrefStoreKeeper() override;
-
-    // Takes ownership of |pref_store|.
-    void Initialize(PrefValueStore* store,
-                    PrefStore* pref_store,
-                    PrefStoreType type);
-
-    PrefStore* store() { return pref_store_.get(); }
-    const PrefStore* store() const { return pref_store_.get(); }
-
-   private:
-    // PrefStore::Observer implementation.
-    void OnPrefValueChanged(const std::string& key) override;
-    void OnInitializationCompleted(bool succeeded) override;
-
-    // PrefValueStore this keeper is part of.
-    PrefValueStore* pref_value_store_;
-
-    // The PrefStore managed by this keeper.
-    scoped_refptr<PrefStore> pref_store_;
-
-    // Type of the pref store.
-    PrefStoreType type_;
-
-    DISALLOW_COPY_AND_ASSIGN(PrefStoreKeeper);
-  };
-
-  typedef std::map<std::string, base::Value::Type> PrefTypeMap;
-
-  // Returns true if the preference with the given name has a value in the
-  // given PrefStoreType, of the same value type as the preference was
-  // registered with.
-  bool PrefValueInStore(const std::string& name, PrefStoreType store) const;
-
-  // Returns true if a preference has an explicit value in any of the
-  // stores in the range specified by |first_checked_store| and
-  // |last_checked_store|, even if that value is currently being
-  // overridden by a higher-priority store.
-  bool PrefValueInStoreRange(const std::string& name,
-                             PrefStoreType first_checked_store,
-                             PrefStoreType last_checked_store) const;
-
-  // Returns the pref store type identifying the source that controls the
-  // Preference identified by |name|. If none of the sources has a value,
-  // INVALID_STORE is returned. In practice, the default PrefStore
-  // should always have a value for any registered preferencem, so INVALID_STORE
-  // indicates an error.
-  PrefStoreType ControllingPrefStoreForPref(const std::string& name) const;
-
-  // Get a value from the specified |store|.
-  bool GetValueFromStore(const std::string& name,
-                         PrefStoreType store,
-                         const base::Value** out_value) const;
-
-  // Get a value from the specified |store| if its |type| matches.
-  bool GetValueFromStoreWithType(const std::string& name,
-                                 base::Value::Type type,
-                                 PrefStoreType store,
-                                 const base::Value** out_value) const;
-
-  // Called upon changes in individual pref stores in order to determine whether
-  // the user-visible pref value has changed. Triggers the change notification
-  // if the effective value of the preference has changed, or if the store
-  // controlling the pref has changed.
-  void NotifyPrefChanged(const std::string& path, PrefStoreType new_store);
-
-  // Called from the PrefStoreKeeper implementation when a pref value for |key|
-  // changed in the pref store for |type|.
-  void OnPrefValueChanged(PrefStoreType type, const std::string& key);
-
-  // Handle the event that the store for |type| has completed initialization.
-  void OnInitializationCompleted(PrefStoreType type, bool succeeded);
-
-  // Initializes a pref store keeper. Sets up a PrefStoreKeeper that will take
-  // ownership of the passed |pref_store|.
-  void InitPrefStore(PrefStoreType type, PrefStore* pref_store);
-
-  // Checks whether initialization is completed and tells the notifier if that
-  // is the case.
-  void CheckInitializationCompleted();
-
-  // Get the PrefStore pointer for the given type. May return NULL if there is
-  // no PrefStore for that type.
-  PrefStore* GetPrefStore(PrefStoreType type) {
-    return pref_stores_[type].store();
-  }
-  const PrefStore* GetPrefStore(PrefStoreType type) const {
-    return pref_stores_[type].store();
-  }
-
-  // Keeps the PrefStore references in order of precedence.
-  PrefStoreKeeper pref_stores_[PREF_STORE_TYPE_MAX + 1];
-
-  PrefChangedCallback pref_changed_callback_;
-
-  // Used for generating notifications. This is a weak reference,
-  // since the notifier is owned by the corresponding PrefService.
-  PrefNotifier* pref_notifier_;
-
-  // A mapping of preference names to their registered types.
-  PrefTypeMap pref_types_;
-
-  // True if not all of the PrefStores were initialized successfully.
-  bool initialization_failed_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrefValueStore);
-};
-
-#endif  // BASE_PREFS_PREF_VALUE_STORE_H_
+// TODO(brettw) remove this forwarding header when prefs is completely moved to
+// components.
+#include "components/prefs/pref_value_store.h"