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/browser_context_keyed_service/browser_context_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 BrowserContextKeyedService {
  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   // BrowserContextKeyedService 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.
  99   // Note that the this function does does not consider the existence of
 100   // policies. An extension is only really able to control a preference if
 101   // PrefService::Preference::IsExtensionModifiable() returns true as well.
 102   bool CanExtensionControlPref(const std::string& extension_id,
 103                                const std::string& pref_key,
 104                                bool incognito) const;
 105
 106   // Removes all "incognito session only" preference values.
 107   void ClearAllIncognitoSessionOnlyPreferences();
 108
 109   // Returns true if an extension identified by |extension_id| controls the
 110   // preference. This means this extension has set a preference value and no
 111   // other extension with higher precedence overrides it. If |from_incognito|
 112   // is not NULL, looks at incognito preferences first, and |from_incognito| is
 113   // set to true if the effective pref value is coming from the incognito
 114   // preferences, false if it is coming from the normal ones.
 115   // Note that the this function does does not consider the existence of
 116   // policies. An extension is only really able to control a preference if
 117   // PrefService::Preference::IsExtensionModifiable() returns true as well.
 118   bool DoesExtensionControlPref(const std::string& extension_id,
 119                                 const std::string& pref_key,
 120                                 bool* from_incognito) const;
 121
 122   // Returns the ID of the extension that currently controls this preference.
 123   // Returns an empty string if this preference is not controlled by an
 124   // extension.
 125   std::string GetExtensionControllingPref(const std::string& pref_key) const;
 126
 127   // Tell the store it's now fully initialized.
 128   void NotifyInitializationCompleted();
 129
 130   // Registers the time when an extension |ext_id| is installed.
 131   void RegisterExtension(const std::string& ext_id,
 132                          const base::Time& install_time,
 133                          bool is_enabled);
 134
 135   // Deletes all entries related to extension |ext_id|.
 136   void UnregisterExtension(const std::string& ext_id);
 137
 138   // Hides or makes the extension preference values of the specified extension
 139   // visible.
 140   void SetExtensionState(const std::string& ext_id, bool is_enabled);
 141
 142   // Adds an observer and notifies it about the currently stored keys.
 143   void AddObserver(Observer* observer);
 144
 145   void RemoveObserver(Observer* observer);
 146
 147   const base::Value* GetEffectivePrefValue(const std::string& key,
 148                                            bool incognito,
 149                                            bool* from_incognito) const;
 150
 151  private:
 152   struct ExtensionEntry;
 153
 154   typedef std::map<std::string, ExtensionEntry*> ExtensionEntryMap;
 155
 156   const PrefValueMap* GetExtensionPrefValueMap(
 157       const std::string& ext_id,
 158       extensions::ExtensionPrefsScope scope) const;
 159
 160   PrefValueMap* GetExtensionPrefValueMap(
 161       const std::string& ext_id,
 162       extensions::ExtensionPrefsScope scope);
 163
 164   // Returns all keys of pref values that are set by the extension of |entry|,
 165   // regardless whether they are set for incognito or regular pref values.
 166   void GetExtensionControlledKeys(const ExtensionEntry& entry,
 167                                   std::set<std::string>* out) const;
 168
 169   // Returns an iterator to the extension which controls the preference |key|.
 170   // If |incognito| is true, looks at incognito preferences first. In that case,
 171   // if |from_incognito| is not NULL, it is set to true if the effective pref
 172   // value is coming from the incognito preferences, false if it is coming from
 173   // the normal ones.
 174   ExtensionEntryMap::const_iterator GetEffectivePrefValueController(
 175       const std::string& key,
 176       bool incognito,
 177       bool* from_incognito) const;
 178
 179   void NotifyOfDestruction();
 180   void NotifyPrefValueChanged(const std::string& key);
 181   void NotifyPrefValueChanged(const std::set<std::string>& keys);
 182
 183   // Mapping of which extension set which preference value. The effective
 184   // preferences values (i.e. the ones with the highest precedence)
 185   // are stored in ExtensionPrefStores.
 186   ExtensionEntryMap entries_;
 187
 188   // In normal Profile shutdown, Shutdown() notifies observers that we are
 189   // being destroyed. In tests, it isn't called, so the notification must
 190   // be done in the destructor. This bit tracks whether it has been done yet.
 191   bool destroyed_;
 192
 193   ObserverList<Observer, true> observers_;
 194
 195   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefValueMap);
 196 };
 197
 198 #endif  // EXTENSIONS_BROWSER_EXTENSION_PREF_VALUE_MAP_H_