Add more per-tab preferences.

chrome/browser/prefs/pref_model_associator.h

Index: chrome/browser/prefs/pref_model_associator.h
diff --git a/chrome/browser/prefs/pref_model_associator.h b/chrome/browser/prefs/pref_model_associator.h
index cf1dd77456d653841425c69c34b5c3dc034af242..3d2fd1f23d20d982461b40693507dc9994dc46f1 100644
--- a/chrome/browser/prefs/pref_model_associator.h
+++ b/chrome/browser/prefs/pref_model_associator.h
@@ -60,6 +60,10 @@ class PrefModelAssociator
   // Returns true if the specified preference is registered for syncing.
   virtual bool IsPrefRegistered(const char* name);
 
+  // Unregisters a previously registered preference. This must be called
+  // prior to making the first sync.
+  virtual void UnregisterPref(const char* name);
+
   // Process a local preference change. This can trigger new SyncChanges being
   // sent to the syncer.
   virtual void ProcessPrefChange(const std::string& name);