Introduce incognito preference settings.

chrome/browser/prefs/pref_service.h

Index: chrome/browser/prefs/pref_service.h
diff --git a/chrome/browser/prefs/pref_service.h b/chrome/browser/prefs/pref_service.h
index 04d7b91348f0307245d14763f090317e45010bcc..dd306c0aa942955bd97c54da924ad3989463d71a 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -42,7 +42,8 @@ class PrefService : public NonThreadSafe {
     // dictionary (a branch), or list.  You shouldn't need to construct this on
     // your own; use the PrefService::Register*Pref methods instead.
     Preference(const PrefService* service,
-               const char* name);
+               const char* name,
+               Value::ValueType type);
     ~Preference() {}
 
     // Returns the name of the Preference (i.e., the key, e.g.,
@@ -92,6 +93,8 @@ class PrefService : public NonThreadSafe {
 
     std::string name_;
 
+    Value::ValueType type_;
+
     // Reference to the PrefService in which this pref was created.
     const PrefService* pref_service_;
 
@@ -105,9 +108,17 @@ class PrefService : public NonThreadSafe {
   // a new PrefService. |extension_pref_store| is used as the source for
   // extension-controlled preferences and may be NULL. The PrefService takes
   // ownership of |extension_pref_store|.
-  static PrefService* CreatePrefService(const FilePath& pref_filename,
-                                        PrefStore* extension_pref_store,
-                                        Profile* profile);
+  static PrefService* CreatePrefService(
+      const FilePath& pref_filename,
+      scoped_refptr<PrefStore> extension_pref_store,
+      Profile* profile);
+
+  // Creates an incognito copy of the pref service that shares most pref stores
+  // but uses a fresh non-persistent overlay for the user pref store and an
+  // individual extension pref store (to cache the effective extension prefs for
+  // incognito windows).
+  PrefService* CreateIncognitoPrefService(
+      scoped_refptr<PrefStore> incognito_extension_prefs);

[Mattias Nissler (ping if slow), 2010/12/20 14:50:02]

We should have a unit test for this, ensuring that values stored in the
incognito service don't end up in the original PrefService.

[battre, 2010/12/21 18:51:59]

Done.

 
   virtual ~PrefService();
 
@@ -225,14 +236,20 @@ class PrefService : public NonThreadSafe {
   // Construct a new pref service, specifying the pref sources as explicit
   // PrefStore pointers. This constructor is what CreatePrefService() ends up
   // calling. It's also used for unit tests.
-  PrefService(PrefStore* managed_platform_prefs,
-              PrefStore* device_management_prefs,
-              PrefStore* extension_prefs,
-              PrefStore* command_line_prefs,
-              PersistentPrefStore* user_prefs,
-              PrefStore* recommended_prefs,
+  PrefService(scoped_refptr<PrefStore> managed_platform_prefs,

[Mattias Nissler (ping if slow), 2010/12/20 14:50:02]

The majority of the codebase passes reference counted objects as plain pointers.
The caller must guarantee that the object is alive in any case, so can you
please check and convert to plain pointers where possible?

+              scoped_refptr<PrefStore> device_management_prefs,
+              scoped_refptr<PrefStore> extension_prefs,
+              scoped_refptr<PrefStore> command_line_prefs,
+              scoped_refptr<PersistentPrefStore> user_prefs,
+              scoped_refptr<PrefStore> recommended_prefs,
               Profile* profile);
 
+  // Constructor to be used only for CreateIncognitoPrefService.

[Mattias Nissler (ping if slow), 2010/12/20 14:50:02]

After pondering this for a while, I'm now leaning towards a different solution:
Can we just keep scoped_refptrs in PrefService for all our stores and use them
to construct a new PrefService using the above constructor from
CreateIncognitoPrefService? That would also obviate the need for the somewhat
fishy PrefValueStore::Derive().

[battre, 2010/12/21 18:51:59]

Done.

+  PrefService(PrefValueStore* old_pref_value_store,
+              scoped_refptr<PersistentPrefStore> old_user_pref_store,
+              scoped_refptr<PrefStore> incognito_extension_prefs,
+              scoped_refptr<DefaultPrefStore> default_store);
+
   // The PrefNotifier handles registering and notifying preference observers.
   // It is created and owned by this PrefService. Subclasses may access it for
   // unit testing.
@@ -274,13 +291,15 @@ class PrefService : public NonThreadSafe {
   scoped_refptr<PrefValueStore> pref_value_store_;
 
   // The persistent pref store used for actual user data.
-  PersistentPrefStore* user_pref_store_;
+  scoped_refptr<PersistentPrefStore> user_pref_store_;
 
   // Points to the default pref store we passed to the PrefValueStore.
-  DefaultPrefStore* default_store_;
+  scoped_refptr<DefaultPrefStore> default_store_;
 
-  // A set of all the registered Preference objects.
-  PreferenceSet prefs_;
+  // Local cache of registered Preference objects. The default_store_
+  // is authoritative with respect to what the types and default values
+  // of registered preferences are.
+  mutable PreferenceSet prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };