Standardize usage of virtual/override/final specifiers in sync/.

sync/api/syncable_service.h

Index: sync/api/syncable_service.h
diff --git a/sync/api/syncable_service.h b/sync/api/syncable_service.h
index 960abc5781fa77d9bc9c89c3bc85db7b0241e2de..f83a017c2da14f1fa08f96b4bcdcc9b760d1c876 100644
--- a/sync/api/syncable_service.h
+++ b/sync/api/syncable_service.h
@@ -63,9 +63,8 @@ class SYNC_EXPORT SyncableService
   // Returns: A default SyncError (IsSet() == false) if no errors were
   //          encountered, and a filled SyncError (IsSet() == true)
   //          otherwise.
-  virtual SyncError ProcessSyncChanges(
-      const tracked_objects::Location& from_here,
-      const SyncChangeList& change_list) override = 0;
+  SyncError ProcessSyncChanges(const tracked_objects::Location& from_here,
+                               const SyncChangeList& change_list) override = 0;
 
   // Returns AttachmentStore used by datatype. Attachment store is used by sync
   // when uploading or downloading attachments.