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- // 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 COMPONENTS_PREFS_PREF_VALUE_STORE_H_
- #define COMPONENTS_PREFS_PREF_VALUE_STORE_H_
- #include <functional>
- #include <map>
- #include <memory>
- #include <string>
- #include <type_traits>
- #include <vector>
- #include "base/callback.h"
- #include "base/memory/raw_ptr.h"
- #include "base/memory/ref_counted.h"
- #include "base/values.h"
- #include "components/prefs/pref_store.h"
- #include "components/prefs/prefs_export.h"
- class PersistentPrefStore;
- class PrefNotifier;
- class PrefRegistry;
- 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 COMPONENTS_PREFS_EXPORT PrefValueStore {
- public:
- using PrefChangedCallback = base::RepeatingCallback<void(const std::string&)>;
- // Delegate used to observe certain events in the |PrefValueStore|'s lifetime.
- class Delegate {
- public:
- virtual ~Delegate() {}
- // Called by the PrefValueStore constructor with the PrefStores passed to
- // it.
- virtual void Init(PrefStore* managed_prefs,
- PrefStore* supervised_user_prefs,
- PrefStore* extension_prefs,
- PrefStore* standalone_browser_prefs,
- PrefStore* command_line_prefs,
- PrefStore* user_prefs,
- PrefStore* recommended_prefs,
- PrefStore* default_prefs,
- PrefNotifier* pref_notifier) = 0;
- virtual void InitIncognitoUserPrefs(
- scoped_refptr<PersistentPrefStore> incognito_user_prefs_overlay,
- scoped_refptr<PersistentPrefStore> incognito_user_prefs_underlay,
- const std::vector<const char*>& overlay_pref_names) = 0;
- virtual void InitPrefRegistry(PrefRegistry* pref_registry) = 0;
- // Called whenever PrefValueStore::UpdateCommandLinePrefStore is called,
- // with the same argument.
- virtual void UpdateCommandLinePrefStore(PrefStore* command_line_prefs) = 0;
- };
- // PrefStores must be listed here in order from highest to lowest priority.
- // MANAGED contains all managed preferences 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 preferences set by extensions.
- // STANDALONE_BROWSER contains system preferences inherited from a separate
- // Chrome instance. One relevant source is extension prefs in lacros
- // passed to ash, so these prefs have similar precedence to extension
- // prefs.
- // COMMAND_LINE contains preferences set by command-line switches.
- // USER contains all user-set preferences.
- // RECOMMENDED contains all preferences that are provided by recommended
- // policies.
- // DEFAULT contains all application default preferences.
- 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,
- STANDALONE_BROWSER_STORE,
- COMMAND_LINE_STORE,
- USER_STORE,
- RECOMMENDED_STORE,
- DEFAULT_STORE,
- PREF_STORE_TYPE_MAX = DEFAULT_STORE
- };
- // 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* standalone_browser_prefs,
- PrefStore* command_line_prefs,
- PrefStore* user_prefs,
- PrefStore* recommended_prefs,
- PrefStore* default_prefs,
- PrefNotifier* pref_notifier,
- std::unique_ptr<Delegate> delegate = nullptr);
- PrefValueStore(const PrefValueStore&) = delete;
- PrefValueStore& operator=(const PrefValueStore&) = delete;
- virtual ~PrefValueStore();
- // Creates a clone of this PrefValueStore with PrefStores overwritten
- // by the parameters passed, if unequal NULL.
- //
- // The new PrefValueStore is passed the |delegate| in its constructor.
- std::unique_ptr<PrefValueStore> CloneAndSpecialize(
- PrefStore* managed_prefs,
- PrefStore* supervised_user_prefs,
- PrefStore* extension_prefs,
- PrefStore* standalone_browser_prefs,
- PrefStore* command_line_prefs,
- PrefStore* user_prefs,
- PrefStore* recommended_prefs,
- PrefStore* default_prefs,
- PrefNotifier* pref_notifier,
- std::unique_ptr<Delegate> delegate = nullptr);
- // 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(PrefChangedCallback callback) {
- pref_changed_callback_ = std::move(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;
- bool PrefValueInStandaloneBrowserStore(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;
- bool PrefValueFromStandaloneBrowserStore(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;
- // Check whether a Preference value is modifiable by a standalone browser
- // (lacros), i.e. whether there is no higher-priority source controlling it.
- bool PrefValueStandaloneBrowserModifiable(const std::string& name) const;
- // Update the command line PrefStore with |command_line_prefs|.
- void UpdateCommandLinePrefStore(PrefStore* command_line_prefs);
- bool IsInitializationComplete() const;
- // Check whether a particular type of PrefStore exists.
- bool HasPrefStore(PrefStoreType type) const;
- private:
- // 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(const PrefStoreKeeper&) = delete;
- PrefStoreKeeper& operator=(const PrefStoreKeeper&) = delete;
- ~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.
- raw_ptr<PrefValueStore> pref_value_store_;
- // The PrefStore managed by this keeper.
- scoped_refptr<PrefStore> pref_store_;
- // Type of the pref store.
- PrefStoreType type_;
- };
- 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.
- raw_ptr<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_;
- // Might be null.
- std::unique_ptr<Delegate> delegate_;
- };
- namespace std {
- template <>
- struct hash<PrefValueStore::PrefStoreType> {
- size_t operator()(PrefValueStore::PrefStoreType type) const {
- return std::hash<
- std::underlying_type<PrefValueStore::PrefStoreType>::type>()(type);
- }
- };
- } // namespace std
- #endif // COMPONENTS_PREFS_PREF_VALUE_STORE_H_
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