[Sync] Refactor sync datatype error handling.

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 15031532fdb0437558c83bbe1613a1eea166e3a0..677020bd7f27bb41c0d319ae6070abdaa01a6935 100644
--- a/chrome/browser/prefs/pref_model_associator.h
+++ b/chrome/browser/prefs/pref_model_associator.h
@@ -37,12 +37,14 @@ class PrefModelAssociator
 
   // SyncableService implementation.
   virtual SyncDataList GetAllSyncData(syncable::ModelType type) const OVERRIDE;
-  virtual void ProcessSyncChanges(const tracked_objects::Location& from_here,
-                                  const SyncChangeList& change_list) OVERRIDE;
+  virtual bool ProcessSyncChanges(const tracked_objects::Location& from_here,
+                                  const SyncChangeList& change_list,
+                                  SyncError* error) OVERRIDE;
   virtual bool MergeDataAndStartSyncing(
       syncable::ModelType type,
       const SyncDataList& initial_sync_data,
-      SyncChangeProcessor* sync_processor) OVERRIDE;
+      SyncChangeProcessor* sync_processor,
+      SyncError* error) OVERRIDE;
   virtual void StopSyncing(syncable::ModelType type) OVERRIDE;
 
   // Returns the list of preference names that are registered as syncable, and