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

sync/engine/syncer_proto_util.h

Index: sync/engine/syncer_proto_util.h
diff --git a/sync/engine/syncer_proto_util.h b/sync/engine/syncer_proto_util.h
index 4e9614c1934348e4773beba7e6eb7ae7f93ab30a..de46091eb30e33a18019b4e0809bd0b3e3a28e3c 100644
--- a/sync/engine/syncer_proto_util.h
+++ b/sync/engine/syncer_proto_util.h
@@ -15,29 +15,29 @@
 #include "sync/sessions/sync_session.h"
 #include "sync/syncable/blob.h"
 
-namespace syncable {
-class Directory;
-class Entry;
-}  // namespace syncable
-
 namespace sync_pb {
 class ClientToServerResponse;
 class EntitySpecifics;
-}  // namespace sync_pb
+}
 
 namespace syncer {
 
-namespace sessions {
-class SyncProtocolError;
-class SyncSessionContext;
-}
-
 class ClientToServerMessage;
 class ThrottledDataTypeTracker;
 class ServerConnectionManager;
 class SyncEntity;
 class CommitResponse_EntryResponse;
 
+namespace sessions {
+class SyncProtocolError;
+class SyncSessionContext;
+}
+
+namespace syncable {
+class Directory;
+class Entry;
+}
+
 class SyncerProtoUtil {
  public:
   // Posts the given message and fills the buffer with the returned value.