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 298d03ce849aed1c541f6688858ec667586392df..56c7deb0df24d324e85ca4385c5911054fb9dd16 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -19,6 +19,16 @@
 // 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
+// - per-extension preferences:
+//       meta-preferences describing properties of the extension like
+//       installation time, whether the extension is enabled, etc.
+// - extension controlled preferences:
+//       global preferences that an individual extension wants to set

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

Maybe not that these are arbitrary preferences (from other subsystems) that the
extension wants to override.

[battre (please use the other), 2010/11/18 16:47:33]

Done.

+//

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

Remove newline.

[battre (please use the other), 2010/11/18 16:47:33]

Done.

 class ExtensionPrefs {
  public:
   // Key name for a preference that keeps track of per-extension settings. This
@@ -73,7 +83,7 @@ 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);
@@ -194,11 +204,22 @@ 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

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

Missing period.

And I think this deserves a more elaborate comment that explains why we would
want to ask the ExtensionPrefs object for a timestamp.

[battre (please use the other), 2010/11/18 16:47:33]

Done.

+  base::Time GetCurrentTime() const;
+
  private:
   // Converts absolute paths in the pref to paths relative to the
   // install_directory_.
@@ -240,6 +261,11 @@ 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;
+
   // Serializes the data and schedules a persistent save via the |PrefService|.
   // Additionally fires a PREF_CHANGED notification with the top-level
   // |kExtensionsPref| path set.
@@ -257,6 +283,28 @@ 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 DictionaryValue* extension) const;

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

Why is that parameter a DictionaryValue*? I'd expect an extension ID.

[battre (please use the other), 2010/11/18 16:47:33]

It is a simple helper method and we need to compare DictionaryValue* elements by
their time. I could add a function std::string GetExtensionId(const
DicationaryValue* extension) and pass the return value to the new
GetInstallTime(std::string) function. But would you recommend to do that?

+
+  // Installs the persistent extension preferences into prefs_'s extension

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

|pref_|'s

[battre (please use the other), 2010/11/18 16:47:33]

Done.

+  // 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)

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

Again, why a Value* and not an extension ID?

[battre (please use the other), 2010/11/18 16:47:33]

this time it is "...Controlle*d*PrefValue", not "Controll*ing*PrefValue". We
could add more indirections. Ask for the winning extension id and then based on
this on its value. Do you prefer this?

+      const;
+
+  // Store the WinningExtensionControlledPrefValue in the PrefValueStore's

[Mattias Nissler (ping if slow), 2010/11/18 16:30:33]

what value? ;) Maybe say it in prose :)

[battre (please use the other), 2010/11/18 16:47:33]

Done.

+  // extension pref store and send notifications to provider in case of
+  // a changed value.
+  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,
+                                      std::vector<std::string> *out) const;
+
   // The pref service specific to this set of extension prefs.
   PrefService* prefs_;