Fix for Bug 50726 "Save extension list and "winning" prefs from extensions"

chrome/browser/extensions/extension_prefs.h

Index: chrome/browser/extensions/extension_prefs.h
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index 11c38430571bcbbbc6eedc8adfd62872c3cfcb8c..3abc0327ece32af507cf6a0036039db583bca8eb 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -19,6 +19,17 @@
 // Class for managing global and per-extension preferences.
 // This class is instantiated by ExtensionsService, so it should be accessed
 // from there.
+//
+// This class distinguishes the following kinds of preferences:
+// - global preferences:
+//       not associated with extensions

[Aaron Boodman, 2010/11/23 20:35:13]

comment nit: maybe: internal state for the extension system in general, not
associated with an individual extension, such as lastUpdateTime.

[battre (please use the other), 2010/11/30 17:46:53]

Done.

+// - per-extension preferences:
+//       meta-preferences describing properties of the extension like

[Aaron Boodman, 2010/11/23 20:35:13]

internal state of an individual extension, such as...

[battre (please use the other), 2010/11/30 17:46:53]

I think "internal state" does not really fit stuff like installation time for
two reasons:
a) "internal state" sounds like "managed by the extension itself" to me.
b) "state" sounds like "can change over time" to me.
I think the current description fits better.

+//       installation time, whether the extension is enabled, etc.
+// - extension controlled preferences:
+//       global preferences that an individual extension wants to set;
+//       these are arbitrary preferences that are controlled by other
+//       sub-systems.

[Aaron Boodman, 2010/11/23 20:35:13]

TODO(aa): Is this information relevant to readers of this class?

[battre (please use the other), 2010/11/30 17:46:53]

Do you refer to the nomenclature of the three different kinds of preference
types? I think we should keep this here. I think that the term "preferences" has
been significantly abused (IMO it describes something the user defines - maybe
indirectly, but an Extension Installation Date is not a preference).

 class ExtensionPrefs {
  public:
   // Key name for a preference that keeps track of per-extension settings. This
@@ -28,6 +39,12 @@ class ExtensionPrefs {
 
   typedef std::vector<linked_ptr<ExtensionInfo> > ExtensionsInfo;
 
+  // Vector containing identifiers for preferences.
+  typedef std::vector<std::string> PrefKeySet;
+
+  // Vector containing identifiers for extensions.
+  typedef std::vector<std::string> ExtensionIdSet;
+
   // This enum is used for the launch type the user wants to use for an
   // application.
   // Do not remove items or re-order this enum as it is used in preferences
@@ -73,7 +90,7 @@ class ExtensionPrefs {
                               bool external_uninstall);
 
   // Returns the state (enabled/disabled) of the given extension.
-  Extension::State GetExtensionState(const std::string& extension_id);
+  Extension::State GetExtensionState(const std::string& extension_id) const;
 
   // Called to change the extension's state when it is enabled/disabled.
   void SetExtensionState(const Extension* extension, Extension::State);
@@ -198,11 +215,23 @@ class ExtensionPrefs {
                         const std::string& data);
   std::string GetUpdateUrlData(const std::string& extension_id);
 
+  // Sets a preference value that is controlled by the extension. In other
+  // words, this is not a pref value *about* the extension but something
+  // global the extension wants to override.
+  void SetExtensionControlledPref(const std::string& extension_id,
+                                  const std::string& pref_key,
+                                  Value* value);
+
   static void RegisterUserPrefs(PrefService* prefs);
 
   // The underlying PrefService.
   PrefService* pref_service() const { return prefs_; }
 
+ protected:
+  // For unit testing. Enables injecting an artificial clock that is used
+  // to query the current time, when an extension is installed.
+  virtual base::Time GetCurrentTime() const;
+
  private:
   // Converts absolute paths in the pref to paths relative to the
   // install_directory_.
@@ -244,6 +273,14 @@ class ExtensionPrefs {
   // Same as above, but returns NULL if it doesn't exist.
   DictionaryValue* GetExtensionPref(const std::string& id) const;
 
+  // Returns the dictionary of preferences controlled by the specified extension
+  // or NULL if unknown. All entries in the dictionary contain non-expanded
+  // paths.
+  DictionaryValue* GetExtensionControlledPrefs(const std::string& id) const;
+
+  // Returns all installed and enabled extensions
+  void GetEnabledExtensions(ExtensionIdSet* out) const;

[Aaron Boodman, 2010/11/23 20:35:13]

This method seems generally useful. Make public?

[battre (please use the other), 2010/11/30 17:46:53]

Done.

+
   // Serializes the data and schedules a persistent save via the |PrefService|.
   // Additionally fires a PREF_CHANGED notification with the top-level
   // |kExtensionsPref| path set.
@@ -261,6 +298,35 @@ class ExtensionPrefs {
   base::Time LastPingDayImpl(const DictionaryValue* dictionary) const;
   void SetLastPingDayImpl(const base::Time& time, DictionaryValue* dictionary);
 
+  // Helper method to acquire the installation time of an extension
+  base::Time GetInstallTime(const std::string& extension_id) const;
+
+  // Grant access to GetInstallTime.
+  friend struct InstallTimeComparator;
+
+  // Fix missing preference entries in the extensions that are were introduced
+  // in a later Chrome version.
+  void FixMissingPrefs(const ExtensionIdSet& extension_ids);
+
+  // Installs the persistent extension preferences into |prefs_|'s extension
+  // pref store.
+  void InstallPersistedExtensionControlledPrefs();
+
+  // Returns the extension controlled preference value of the extension that was
+  // installed most recently.
+  const Value* WinningExtensionControlledPrefValue(const std::string& key)
+      const;
+
+  // Find the most recently installed extension that defines a preference
+  // for |pref_key|, then store its value in the PrefValueStore's extension pref
+  // store and send notifications to observers in case the value changed.
+  void UpdateWinningPref(const std::string& pref_key);
+
+  // Retrieves a list of preference keys that the specified extension
+  // intents to manage.
+  void GetExtensionControlledPrefKeys(const std::string& extension_id,
+                                      PrefKeySet *out) const;
+
   // The pref service specific to this set of extension prefs.
   PrefService* prefs_;