extensions/browser/extension_pref_value_map.h

   1 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_PREF_VALUE_MAP_H_
   6 #define EXTENSIONS_BROWSER_EXTENSION_PREF_VALUE_MAP_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/observer_list.h"
  13 #include "base/prefs/pref_value_map.h"
  14 #include "base/time/time.h"
  15 #include "base/values.h"
  16 #include "components/keyed_service/core/keyed_service.h"
  17 #include "extensions/browser/extension_prefs_scope.h"
  18
  19 // Non-persistent data container that is shared by ExtensionPrefStores. All
  20 // extension pref values (incognito and regular) are stored herein and
  21 // provided to ExtensionPrefStores.
  22 //
  23 // The semantics of the ExtensionPrefValueMap are:
  24 // - A regular setting applies to regular browsing sessions as well as incognito
  25 //   browsing sessions.
  26 // - An incognito setting applies only to incognito browsing sessions, not to
  27 //   regular ones. It takes precedence over a regular setting set by the same
  28 //   extension.
  29 // - A regular-only setting applies only to regular browsing sessions, not to
  30 //   incognito ones. It takes precedence over a regular setting set by the same
  31 //   extension.
  32 // - If two different extensions set a value for the same preference (and both
  33 //   values apply to the regular/incognito browsing session), the extension that
  34 //   was installed later takes precedence, regardless of whether the settings
  35 //   are regular, incognito or regular-only.
  36 //
  37 // The following table illustrates the behavior:
  38 //   A.reg | A.reg_only | A.inc | B.reg | B.reg_only | B.inc | E.reg | E.inc
  39 //     1   |      -     |   -   |   -   |      -     |   -   |   1   |   1
  40 //     1   |      2     |   -   |   -   |      -     |   -   |   2   |   1
  41 //     1   |      -     |   3   |   -   |      -     |   -   |   1   |   3
  42 //     1   |      2     |   3   |   -   |      -     |   -   |   2   |   3
  43 //     1   |      -     |   -   |   4   |      -     |   -   |   4   |   4
  44 //     1   |      2     |   3   |   4   |      -     |   -   |   4   |   4
  45 //     1   |      -     |   -   |   -   |      5     |   -   |   5   |   1
  46 //     1   |      -     |   3   |   4   |      5     |   -   |   5   |   4
  47 //     1   |      -     |   -   |   -   |      -     |   6   |   1   |   6
  48 //     1   |      2     |   -   |   4   |      -     |   6   |   4   |   6
  49 //     1   |      2     |   3   |   -   |      5     |   6   |   5   |   6
  50 //
  51 // A = extension A, B = extension B, E = effective value
  52 // .reg = regular value
  53 // .reg_only = regular-only value
  54 // .inc = incognito value
  55 // Extension B has higher precedence than A.
  56 class ExtensionPrefValueMap : public KeyedService {
  57  public:
  58   // Observer interface for monitoring ExtensionPrefValueMap.
  59   class Observer {
  60    public:
  61     // Called when the value for the given |key| set by one of the extensions
  62     // changes. This does not necessarily mean that the effective value has
  63     // changed.
  64     virtual void OnPrefValueChanged(const std::string& key) = 0;
  65     // Notification about the ExtensionPrefValueMap being fully initialized.
  66     virtual void OnInitializationCompleted() = 0;
  67     // Called when the ExtensionPrefValueMap is being destroyed. When called,
  68     // observers must unsubscribe.
  69     virtual void OnExtensionPrefValueMapDestruction() = 0;
  70
  71    protected:
  72     virtual ~Observer() {}
  73   };
  74
  75   ExtensionPrefValueMap();
  76   virtual ~ExtensionPrefValueMap();
  77
  78   // KeyedService implementation.
  79   virtual void Shutdown() OVERRIDE;
  80
  81   // Set an extension preference |value| for |key| of extension |ext_id|.
  82   // Takes ownership of |value|.
  83   // Note that regular extension pref values need to be reported to
  84   // incognito and to regular ExtensionPrefStores.
  85   // Precondition: the extension must be registered.
  86   void SetExtensionPref(const std::string& ext_id,
  87                         const std::string& key,
  88                         extensions::ExtensionPrefsScope scope,
  89                         base::Value* value);
  90
  91   // Remove the extension preference value for |key| of extension |ext_id|.
  92   // Precondition: the extension must be registered.
  93   void RemoveExtensionPref(const std::string& ext_id,
  94                            const std::string& key,
  95                            extensions::ExtensionPrefsScope scope);
  96
  97   // Returns true if currently no extension with higher precedence controls the
  98   // preference. If |incognito| is true and the extension does not have
  99   // incognito permission, CanExtensionControlPref returns false.
 100   // Note that this function does does not consider the existence of
 101   // policies. An extension is only really able to control a preference if
 102   // PrefService::Preference::IsExtensionModifiable() returns true as well.
 103   bool CanExtensionControlPref(const std::string& extension_id,
 104                                const std::string& pref_key,
 105                                bool incognito) const;
 106
 107   // Removes all "incognito session only" preference values.
 108   void ClearAllIncognitoSessionOnlyPreferences();
 109
 110   // Returns true if an extension identified by |extension_id| controls the
 111   // preference. This means this extension has set a preference value and no
 112   // other extension with higher precedence overrides it. If |from_incognito|
 113   // is not NULL, looks at incognito preferences first, and |from_incognito| is
 114   // set to true if the effective pref value is coming from the incognito
 115   // preferences, false if it is coming from the normal ones.
 116   // Note that the this function does does not consider the existence of
 117   // policies. An extension is only really able to control a preference if
 118   // PrefService::Preference::IsExtensionModifiable() returns true as well.
 119   bool DoesExtensionControlPref(const std::string& extension_id,
 120                                 const std::string& pref_key,
 121                                 bool* from_incognito) const;
 122
 123   // Returns the ID of the extension that currently controls this preference
 124   // for a regular profile. Incognito settings are ignored.
 125   // Returns an empty string if this preference is not controlled by an
 126   // extension.
 127   std::string GetExtensionControllingPref(const std::string& pref_key) const;
 128
 129   // Tell the store it's now fully initialized.
 130   void NotifyInitializationCompleted();
 131
 132   // Registers the time when an extension |ext_id| is installed.
 133   void RegisterExtension(const std::string& ext_id,
 134                          const base::Time& install_time,
 135                          bool is_enabled,
 136                          bool is_incognito_enabled);
 137
 138   // Deletes all entries related to extension |ext_id|.
 139   void UnregisterExtension(const std::string& ext_id);
 140
 141   // Hides or makes the extension preference values of the specified extension
 142   // visible.
 143   void SetExtensionState(const std::string& ext_id, bool is_enabled);
 144
 145   // Sets whether the extension has permission to access incognito state.
 146   void SetExtensionIncognitoState(const std::string& ext_id,
 147                                   bool is_incognito_enabled);
 148
 149   // Adds an observer and notifies it about the currently stored keys.
 150   void AddObserver(Observer* observer);
 151
 152   void RemoveObserver(Observer* observer);
 153
 154   const base::Value* GetEffectivePrefValue(const std::string& key,
 155                                            bool incognito,
 156                                            bool* from_incognito) const;
 157
 158  private:
 159   struct ExtensionEntry;
 160
 161   typedef std::map<std::string, ExtensionEntry*> ExtensionEntryMap;
 162
 163   const PrefValueMap* GetExtensionPrefValueMap(
 164       const std::string& ext_id,
 165       extensions::ExtensionPrefsScope scope) const;
 166
 167   PrefValueMap* GetExtensionPrefValueMap(
 168       const std::string& ext_id,
 169       extensions::ExtensionPrefsScope scope);
 170
 171   // Returns all keys of pref values that are set by the extension of |entry|,
 172   // regardless whether they are set for incognito or regular pref values.
 173   void GetExtensionControlledKeys(const ExtensionEntry& entry,
 174                                   std::set<std::string>* out) const;
 175
 176   // Returns an iterator to the extension which controls the preference |key|.
 177   // If |incognito| is true, looks at incognito preferences first. In that case,
 178   // if |from_incognito| is not NULL, it is set to true if the effective pref
 179   // value is coming from the incognito preferences, false if it is coming from
 180   // the normal ones.
 181   ExtensionEntryMap::const_iterator GetEffectivePrefValueController(
 182       const std::string& key,
 183       bool incognito,
 184       bool* from_incognito) const;
 185
 186   void NotifyOfDestruction();
 187   void NotifyPrefValueChanged(const std::string& key);
 188   void NotifyPrefValueChanged(const std::set<std::string>& keys);
 189
 190   // Mapping of which extension set which preference value. The effective
 191   // preferences values (i.e. the ones with the highest precedence)
 192   // are stored in ExtensionPrefStores.
 193   ExtensionEntryMap entries_;
 194
 195   // In normal Profile shutdown, Shutdown() notifies observers that we are
 196   // being destroyed. In tests, it isn't called, so the notification must
 197   // be done in the destructor. This bit tracks whether it has been done yet.
 198   bool destroyed_;
 199
 200   ObserverList<Observer, true> observers_;
 201
 202   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefValueMap);
 203 };
 204
 205 #endif  // EXTENSIONS_BROWSER_EXTENSION_PREF_VALUE_MAP_H_