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

sync/syncable/directory.h

Index: sync/syncable/directory.h
diff --git a/sync/syncable/directory.h b/sync/syncable/directory.h
index a7f7fe185c8da48fbc32590221e0e1e917ebaa16..73330ec69c16ad0a8b3400e5ce2385451277ad16 100644
--- a/sync/syncable/directory.h
+++ b/sync/syncable/directory.h
@@ -21,9 +21,9 @@
 #include "sync/util/cryptographer.h"
 
 namespace syncer {
+
 class Encryptor;
 class UnrecoverableErrorHandler;
-}
 
 namespace syncable {
 
@@ -606,5 +606,6 @@ class Directory {
 };
 
 }  // namespace syncable
+}  // namespace syncer
 
 #endif // SYNC_SYNCABLE_DIRECTORY_H_