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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_PREFS_PREF_VALUE_STORE_H_
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#define BASE_PREFS_PREF_VALUE_STORE_H_
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#include "base/basictypes.h"
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#include "base/callback.h"
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#include "base/gtest_prod_util.h"
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#include "base/memory/ref_counted.h"
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#include "base/prefs/base_prefs_export.h"
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#include "base/prefs/pref_store.h"
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#include "base/values.h"
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// The PrefValueStore manages various sources of values for Preferences
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// (e.g., configuration policies, extensions, and user settings). It returns
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// the value of a Preference from the source with the highest priority, and
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// allows setting user-defined values for preferences that are not managed.
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// Unless otherwise explicitly noted, all of the methods of this class must
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// be called on the UI thread.
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class BASE_PREFS_EXPORT PrefValueStore {
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typedef base::Callback<void(const std::string&)> PrefChangedCallback;
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// In decreasing order of precedence:
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// |managed_prefs| contains all preferences from mandatory policies.
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// |supervised_user_prefs| contains all preferences from supervised user
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// settings, i.e. settings configured for a supervised user by their
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// |extension_prefs| contains preference values set by extensions.
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// |command_line_prefs| contains preference values set by command-line
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// |user_prefs| contains all user-set preference values.
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// |recommended_prefs| contains all preferences from recommended policies.
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// |default_prefs| contains application-default preference values. It must
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// be non-null if any preferences are to be registered.
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// |pref_notifier| facilitates broadcasting preference change notifications
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PrefValueStore(PrefStore* managed_prefs,
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PrefStore* supervised_user_prefs,
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PrefStore* extension_prefs,
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PrefStore* command_line_prefs,
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PrefStore* user_prefs,
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PrefStore* recommended_prefs,
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PrefStore* default_prefs,
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PrefNotifier* pref_notifier);
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virtual ~PrefValueStore();
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// Creates a clone of this PrefValueStore with PrefStores overwritten
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// by the parameters passed, if unequal NULL.
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PrefValueStore* CloneAndSpecialize(PrefStore* managed_prefs,
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PrefStore* supervised_user_prefs,
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PrefStore* extension_prefs,
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PrefStore* command_line_prefs,
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PrefStore* user_prefs,
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PrefStore* recommended_prefs,
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PrefStore* default_prefs,
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PrefNotifier* pref_notifier);
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// A PrefValueStore can have exactly one callback that is directly
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// notified of preferences changing in the store. This does not
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// filter through the PrefNotifier mechanism, which may not forward
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// certain changes (e.g. unregistered prefs).
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void set_callback(const PrefChangedCallback& callback);
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// Gets the value for the given preference name that has the specified value
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// type. Values stored in a PrefStore that have the matching |name| but
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// a non-matching |type| are silently skipped. Returns true if a valid value
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// was found in any of the available PrefStores. Most callers should use
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// Preference::GetValue() instead of calling this method directly.
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bool GetValue(const std::string& name,
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base::Value::Type type,
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const base::Value** out_value) const;
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// Gets the recommended value for the given preference name that has the
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// specified value type. A value stored in the recommended PrefStore that has
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// the matching |name| but a non-matching |type| is silently ignored. Returns
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// true if a valid value was found. Most callers should use
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// Preference::GetRecommendedValue() instead of calling this method directly.
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bool GetRecommendedValue(const std::string& name,
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base::Value::Type type,
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const base::Value** out_value) const;
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// These methods return true if a preference with the given name is in the
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// indicated pref store, even if that value is currently being overridden by
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// a higher-priority source.
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bool PrefValueInManagedStore(const char* name) const;
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bool PrefValueInExtensionStore(const char* name) const;
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bool PrefValueInUserStore(const char* name) const;
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// These methods return true if a preference with the given name is actually
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// being controlled by the indicated pref store and not being overridden by
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// a higher-priority source.
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bool PrefValueFromExtensionStore(const char* name) const;
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bool PrefValueFromUserStore(const char* name) const;
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bool PrefValueFromRecommendedStore(const char* name) const;
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bool PrefValueFromDefaultStore(const char* name) const;
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// Check whether a Preference value is modifiable by the user, i.e. whether
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// there is no higher-priority source controlling it.
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bool PrefValueUserModifiable(const char* name) const;
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// Check whether a Preference value is modifiable by an extension, i.e.
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// whether there is no higher-priority source controlling it.
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bool PrefValueExtensionModifiable(const char* name) const;
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// Update the command line PrefStore with |command_line_prefs|.
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void UpdateCommandLinePrefStore(PrefStore* command_line_prefs);
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// PrefStores must be listed here in order from highest to lowest priority.
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// MANAGED contains all managed preference values that are provided by
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// mandatory policies (e.g. Windows Group Policy or cloud policy).
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// SUPERVISED_USER contains preferences that are valid for supervised users.
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// EXTENSION contains preference values set by extensions.
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// COMMAND_LINE contains preference values set by command-line switches.
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// USER contains all user-set preference values.
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// RECOMMENDED contains all preferences that are provided by recommended
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// DEFAULT contains all application default preference values.
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// INVALID_STORE is not associated with an actual PrefStore but used as
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// an invalid marker, e.g. as a return value.
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SUPERVISED_USER_STORE,
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PREF_STORE_TYPE_MAX = DEFAULT_STORE
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// Keeps a PrefStore reference on behalf of the PrefValueStore and monitors
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// the PrefStore for changes, forwarding notifications to PrefValueStore. This
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// indirection is here for the sake of disambiguating notifications from the
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// individual PrefStores.
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class PrefStoreKeeper : public PrefStore::Observer {
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virtual ~PrefStoreKeeper();
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// Takes ownership of |pref_store|.
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void Initialize(PrefValueStore* store,
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PrefStore* pref_store,
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PrefStore* store() { return pref_store_.get(); }
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const PrefStore* store() const { return pref_store_.get(); }
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// PrefStore::Observer implementation.
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virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
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virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
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// PrefValueStore this keeper is part of.
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PrefValueStore* pref_value_store_;
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// The PrefStore managed by this keeper.
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scoped_refptr<PrefStore> pref_store_;
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// Type of the pref store.
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DISALLOW_COPY_AND_ASSIGN(PrefStoreKeeper);
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typedef std::map<std::string, base::Value::Type> PrefTypeMap;
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friend class PrefValueStorePolicyRefreshTest;
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FRIEND_TEST_ALL_PREFIXES(PrefValueStorePolicyRefreshTest, TestPolicyRefresh);
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FRIEND_TEST_ALL_PREFIXES(PrefValueStorePolicyRefreshTest,
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TestRefreshPolicyPrefsCompletion);
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FRIEND_TEST_ALL_PREFIXES(PrefValueStorePolicyRefreshTest,
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TestConcurrentPolicyRefresh);
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// Returns true if the preference with the given name has a value in the
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// given PrefStoreType, of the same value type as the preference was
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bool PrefValueInStore(const char* name, PrefStoreType store) const;
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// Returns true if a preference has an explicit value in any of the
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// stores in the range specified by |first_checked_store| and
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// |last_checked_store|, even if that value is currently being
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// overridden by a higher-priority store.
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bool PrefValueInStoreRange(const char* name,
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PrefStoreType first_checked_store,
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PrefStoreType last_checked_store) const;
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// Returns the pref store type identifying the source that controls the
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// Preference identified by |name|. If none of the sources has a value,
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// INVALID_STORE is returned. In practice, the default PrefStore
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// should always have a value for any registered preferencem, so INVALID_STORE
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// indicates an error.
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PrefStoreType ControllingPrefStoreForPref(const char* name) const;
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// Get a value from the specified |store|.
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bool GetValueFromStore(const char* name,
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const base::Value** out_value) const;
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// Get a value from the specified |store| if its |type| matches.
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bool GetValueFromStoreWithType(const char* name,
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base::Value::Type type,
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const base::Value** out_value) const;
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// Called upon changes in individual pref stores in order to determine whether
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// the user-visible pref value has changed. Triggers the change notification
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// if the effective value of the preference has changed, or if the store
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// controlling the pref has changed.
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void NotifyPrefChanged(const char* path, PrefStoreType new_store);
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// Called from the PrefStoreKeeper implementation when a pref value for |key|
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// changed in the pref store for |type|.
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void OnPrefValueChanged(PrefStoreType type, const std::string& key);
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// Handle the event that the store for |type| has completed initialization.
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void OnInitializationCompleted(PrefStoreType type, bool succeeded);
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// Initializes a pref store keeper. Sets up a PrefStoreKeeper that will take
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// ownership of the passed |pref_store|.
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void InitPrefStore(PrefStoreType type, PrefStore* pref_store);
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// Checks whether initialization is completed and tells the notifier if that
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void CheckInitializationCompleted();
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// Get the PrefStore pointer for the given type. May return NULL if there is
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// no PrefStore for that type.
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PrefStore* GetPrefStore(PrefStoreType type) {
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return pref_stores_[type].store();
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const PrefStore* GetPrefStore(PrefStoreType type) const {
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return pref_stores_[type].store();
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// Keeps the PrefStore references in order of precedence.
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PrefStoreKeeper pref_stores_[PREF_STORE_TYPE_MAX + 1];
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PrefChangedCallback pref_changed_callback_;
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// Used for generating notifications. This is a weak reference,
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// since the notifier is owned by the corresponding PrefService.
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PrefNotifier* pref_notifier_;
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// A mapping of preference names to their registered types.
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PrefTypeMap pref_types_;
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// True if not all of the PrefStores were initialized successfully.
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bool initialization_failed_;
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DISALLOW_COPY_AND_ASSIGN(PrefValueStore);
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#endif // BASE_PREFS_PREF_VALUE_STORE_H_