Introduce per-tab preferences service.

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 3002e9d38db81480ae78cf854f8ab7f3849b53cb..c9821f6c094dfa965068b2433659d86efdf6699c 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -146,6 +146,10 @@ class PrefService : public base::NonThreadSafe {
   // incognito windows).
   PrefService* CreateIncognitoPrefService(PrefStore* incognito_extension_prefs);
 
+  // Creates a per-tab copy of the pref service that shares most pref stores
+  // and allows WebKit-related preferences to be overridden on per-tab basis.
+  PrefService* CreatePrefServiceWithPerTabPrefStore();
+
   virtual ~PrefService();
 
   // Reloads the data from file. This should only be called when the importer
@@ -297,24 +301,28 @@ class PrefService : public base::NonThreadSafe {
   SyncableService* GetSyncableService();
 
  protected:
-  // 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* managed_cloud_prefs,
-              PrefStore* extension_prefs,
-              PrefStore* command_line_prefs,
+  // Construct a new pref service. This constructor is what
+  // factory methods end up calling and what is used for unit tests.
+  PrefService(PrefNotifierImpl* pref_notifier,
               PersistentPrefStore* user_prefs,
-              PrefStore* recommended_platform_prefs,
-              PrefStore* recommended_cloud_prefs,
               DefaultPrefStore* default_store,
+              PrefModelAssociator* pref_sync_associator,
+              PrefValueStore* pref_value_store,
               bool async);
 
+  // The following fields are made protected for unit testing.
+
   // The PrefNotifier handles registering and notifying preference observers.
-  // It is created and owned by this PrefService. Subclasses may access it for
-  // unit testing.
+  // It is created and owned by this PrefService.
   scoped_ptr<PrefNotifierImpl> pref_notifier_;
 
+  // Pref Stores and profile that we pass to the PrefValueStore.
+  scoped_refptr<PersistentPrefStore> user_pref_store_;
+  scoped_refptr<DefaultPrefStore> default_store_;
+
+  // The model associator that maintains the links with the sync db.
+  scoped_ptr<PrefModelAssociator> pref_sync_associator_;
+
  private:
   class PreferencePathComparator {
    public:
@@ -338,11 +346,6 @@ class PrefService : public base::NonThreadSafe {
   // Give access to ReportUserPrefChanged() and GetMutableUserPref().
   friend class subtle::ScopedUserPrefUpdateBase;
 
-  // Construct an incognito version of the pref service. Use
-  // CreateIncognitoPrefService() instead of calling this constructor directly.
-  PrefService(const PrefService& original,
-              PrefStore* incognito_extension_prefs);
-
   // Sends notification of a changed preference. This needs to be called by
   // a ScopedUserPrefUpdate if a DictionaryValue or ListValue is changed.
   void ReportUserPrefChanged(const std::string& key);
@@ -382,21 +385,14 @@ class PrefService : public base::NonThreadSafe {
   base::Value* GetMutableUserPref(const char* path,
                                   base::Value::Type type);
 
-  // The PrefValueStore provides prioritized preference values. It is created
-  // and owned by this PrefService. Subclasses may access it for unit testing.
-  scoped_ptr<PrefValueStore> pref_value_store_;
-
-  // Pref Stores and profile that we passed to the PrefValueStore.
-  scoped_refptr<PersistentPrefStore> user_pref_store_;
-  scoped_refptr<DefaultPrefStore> default_store_;
-
   // 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_;
 
-  // The model associator that maintains the links with the sync db.
-  scoped_ptr<PrefModelAssociator> pref_sync_associator_;
+  // The PrefValueStore provides prioritized preference values. It is created
+  // and owned by this PrefService. Subclasses may access it for unit testing.

[Mattias Nissler (ping if slow), 2011/11/18 14:57:07]

nit: It's not necessarily created by the PrefService any longer.

[mnaganov (inactive), 2011/11/21 14:52:20]

Done.

+  scoped_ptr<PrefValueStore> pref_value_store_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };