[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 b66a6e525e2d828928214670c1d636fe3fb7c98c..8bae8f38a6f0671b83e3e0991e91eceaea3fe52b 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 {
 
@@ -617,5 +617,6 @@ class Directory {
 };
 
 }  // namespace syncable
+}  // namespace syncer
 
 #endif // SYNC_SYNCABLE_DIRECTORY_H_