Add PrinterSpecifics to the sync protos.

components/sync/driver/model_association_manager.cc

Index: components/sync/driver/model_association_manager.cc
diff --git a/components/sync/driver/model_association_manager.cc b/components/sync/driver/model_association_manager.cc
index 55d59286000fdff6525982f488b576fe276d8d79..52fb195cd87940f784cafe157744bed8447f2969 100644
--- a/components/sync/driver/model_association_manager.cc
+++ b/components/sync/driver/model_association_manager.cc
@@ -47,9 +47,9 @@ static const syncer::ModelType kStartOrder[] = {
     syncer::APPS, syncer::APP_LIST, syncer::ARC_PACKAGE, syncer::THEMES,
     syncer::SEARCH_ENGINES, syncer::SESSIONS, syncer::APP_NOTIFICATIONS,
     syncer::DICTIONARY, syncer::FAVICON_IMAGES, syncer::FAVICON_TRACKING,
-    syncer::SUPERVISED_USER_SETTINGS, syncer::SUPERVISED_USER_SHARED_SETTINGS,
-    syncer::SUPERVISED_USER_WHITELISTS, syncer::ARTICLES,
-    syncer::WIFI_CREDENTIALS,
+    syncer::PRINTER, syncer::SUPERVISED_USER_SETTINGS,
+    syncer::SUPERVISED_USER_SHARED_SETTINGS, syncer::SUPERVISED_USER_WHITELISTS,
+    syncer::ARTICLES, syncer::WIFI_CREDENTIALS,
 };
 
 static_assert(arraysize(kStartOrder) ==