WIP: Introduce per-TabContents PrefService.

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 5361928c981c6c60149af59ab60a978f41a502bf..6f20ab6cde8cb3bcbe9b78658dfe557fec66c1ff 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -143,6 +143,11 @@ class PrefService : public base::NonThreadSafe {
   // incognito windows).
   PrefService* CreateIncognitoPrefService(PrefStore* incognito_extension_prefs);
 
+  // Creates a per-TabContents pref service derived from this PrefService. The
+  // new PrefService will share all PrefStores with the base PrefService, except
+  // for user prefs. Also, it manages a separate set of registered prefs.
+  PrefService* CreateTabContentsPrefService();
+
   virtual ~PrefService();
 
   // Reloads the data from file. This should only be called when the importer
@@ -294,17 +299,12 @@ 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 CreatePrefService()
+  // ends up calling. It's also used for unit tests.
+  PrefService(PrefValueStore* pref_value_store,
               PersistentPrefStore* user_prefs,
-              PrefStore* recommended_platform_prefs,
-              PrefStore* recommended_cloud_prefs,
               DefaultPrefStore* default_store,
+              PrefNotifierImpl* pref_notifier,
               bool async);
 
   // The PrefNotifier handles registering and notifying preference observers.
@@ -335,11 +335,6 @@ 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);