[Sync] Move sync/{internal_api,syncable} into syncer namespace

sync/engine/verify_updates_command.h

Index: sync/engine/verify_updates_command.h
diff --git a/sync/engine/verify_updates_command.h b/sync/engine/verify_updates_command.h
index 27b0b418b91860c2745dd1c011fb0060e9938ac2..cc1193593e8c5f3cec57ac92143c391228e2ae1f 100644
--- a/sync/engine/verify_updates_command.h
+++ b/sync/engine/verify_updates_command.h
@@ -13,12 +13,12 @@
 #include "sync/engine/syncproto.h"
 #include "sync/internal_api/public/engine/model_safe_worker.h"
 
+namespace syncer {
+
 namespace syncable {
 class WriteTransaction;
 }
 
-namespace syncer {
-
 // Verifies the response from a GetUpdates request. All invalid updates will be
 // noted in the SyncSession after this command is executed.
 class VerifyUpdatesCommand : public ModelChangingSyncerCommand {