diff --git a/quic/test_tools/quic_flow_controller_peer.h b/quic/test_tools/quic_flow_controller_peer.h
new file mode 100644
index 0000000..1dc5a1a
--- /dev/null
+++ b/quic/test_tools/quic_flow_controller_peer.h
@@ -0,0 +1,46 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef QUICHE_QUIC_TEST_TOOLS_QUIC_FLOW_CONTROLLER_PEER_H_
+#define QUICHE_QUIC_TEST_TOOLS_QUIC_FLOW_CONTROLLER_PEER_H_
+
+#include "base/macros.h"
+#include "net/third_party/quiche/src/quic/core/quic_packets.h"
+
+namespace quic {
+
+class QuicFlowController;
+
+namespace test {
+
+class QuicFlowControllerPeer {
+ public:
+  QuicFlowControllerPeer() = delete;
+
+  static void SetSendWindowOffset(QuicFlowController* flow_controller,
+                                  QuicStreamOffset offset);
+
+  static void SetReceiveWindowOffset(QuicFlowController* flow_controller,
+                                     QuicStreamOffset offset);
+
+  static void SetMaxReceiveWindow(QuicFlowController* flow_controller,
+                                  QuicByteCount window_size);
+
+  static QuicStreamOffset SendWindowOffset(QuicFlowController* flow_controller);
+
+  static QuicByteCount SendWindowSize(QuicFlowController* flow_controller);
+
+  static QuicStreamOffset ReceiveWindowOffset(
+      QuicFlowController* flow_controller);
+
+  static QuicByteCount ReceiveWindowSize(QuicFlowController* flow_controller);
+
+  static QuicByteCount WindowUpdateThreshold(
+      QuicFlowController* flow_controller);
+};
+
+}  // namespace test
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_TEST_TOOLS_QUIC_FLOW_CONTROLLER_PEER_H_