diff --git a/quic/masque/masque_server_backend.h b/quic/masque/masque_server_backend.h
new file mode 100644
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+++ b/quic/masque/masque_server_backend.h
@@ -0,0 +1,68 @@
+// Copyright 2019 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_MASQUE_MASQUE_SERVER_BACKEND_H_
+#define QUICHE_QUIC_MASQUE_MASQUE_SERVER_BACKEND_H_
+
+#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+#include "net/third_party/quiche/src/quic/tools/quic_memory_cache_backend.h"
+
+namespace quic {
+
+// QUIC server backend that understands MASQUE requests, but otherwise answers
+// HTTP queries using an in-memory cache.
+class QUIC_NO_EXPORT MasqueServerBackend : public QuicMemoryCacheBackend {
+ public:
+  // Interface meant to be implemented by the owner of the MasqueServerBackend
+  // instance.
+  class QUIC_NO_EXPORT BackendClient {
+   public:
+    virtual std::unique_ptr<QuicBackendResponse> HandleMasqueRequest(
+        const std::string& masque_path,
+        const spdy::SpdyHeaderBlock& request_headers,
+        const std::string& request_body,
+        QuicSimpleServerBackend::RequestHandler* request_handler) = 0;
+    virtual ~BackendClient() = default;
+  };
+
+  explicit MasqueServerBackend(const std::string& server_authority,
+                               const std::string& cache_directory);
+
+  // Disallow copy and assign.
+  MasqueServerBackend(const MasqueServerBackend&) = delete;
+  MasqueServerBackend& operator=(const MasqueServerBackend&) = delete;
+
+  // From QuicMemoryCacheBackend.
+  void FetchResponseFromBackend(
+      const spdy::SpdyHeaderBlock& request_headers,
+      const std::string& request_body,
+      QuicSimpleServerBackend::RequestHandler* request_handler) override;
+
+  void CloseBackendResponseStream(
+      QuicSimpleServerBackend::RequestHandler* request_handler) override;
+
+  // Register backend client that can handle MASQUE requests.
+  void RegisterBackendClient(QuicConnectionId connection_id,
+                             BackendClient* backend_client);
+
+  // Unregister backend client.
+  void RemoveBackendClient(QuicConnectionId connection_id);
+
+ private:
+  // Handle MASQUE request.
+  bool MaybeHandleMasqueRequest(
+      const spdy::SpdyHeaderBlock& request_headers,
+      const std::string& request_body,
+      QuicSimpleServerBackend::RequestHandler* request_handler);
+
+  std::string server_authority_;
+  QuicUnorderedMap<std::string, std::unique_ptr<QuicBackendResponse>>
+      active_response_map_;
+  QuicUnorderedMap<QuicConnectionId, BackendClient*, QuicConnectionIdHash>
+      backend_clients_;
+};
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_MASQUE_MASQUE_SERVER_BACKEND_H_