diff --git a/quiche/quic/tools/quic_memory_cache_backend.h b/quiche/quic/tools/quic_memory_cache_backend.h
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+++ b/quiche/quic/tools/quic_memory_cache_backend.h
@@ -0,0 +1,217 @@
+// Copyright (c) 2012 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_TOOLS_QUIC_MEMORY_CACHE_BACKEND_H_
+#define QUICHE_QUIC_TOOLS_QUIC_MEMORY_CACHE_BACKEND_H_
+
+#include <list>
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "absl/container/flat_hash_map.h"
+#include "absl/strings/string_view.h"
+#include "quiche/quic/core/http/spdy_utils.h"
+#include "quiche/quic/platform/api/quic_containers.h"
+#include "quiche/quic/platform/api/quic_mutex.h"
+#include "quiche/quic/tools/quic_backend_response.h"
+#include "quiche/quic/tools/quic_simple_server_backend.h"
+#include "quiche/quic/tools/quic_url.h"
+#include "quiche/spdy/core/spdy_framer.h"
+
+namespace quic {
+
+// In-memory cache for HTTP responses.
+// Reads from disk cache generated by:
+// `wget -p --save_headers <url>`
+class QuicMemoryCacheBackend : public QuicSimpleServerBackend {
+ public:
+  // Class to manage loading a resource file into memory.  There are
+  // two uses: called by InitializeBackend to load resources
+  // from files, and recursively called when said resources specify
+  // server push associations.
+  class ResourceFile {
+   public:
+    explicit ResourceFile(const std::string& file_name);
+    ResourceFile(const ResourceFile&) = delete;
+    ResourceFile& operator=(const ResourceFile&) = delete;
+    virtual ~ResourceFile();
+
+    void Read();
+
+    // |base| is |file_name_| with |cache_directory| prefix stripped.
+    void SetHostPathFromBase(absl::string_view base);
+
+    const std::string& file_name() { return file_name_; }
+
+    absl::string_view host() { return host_; }
+
+    absl::string_view path() { return path_; }
+
+    const spdy::Http2HeaderBlock& spdy_headers() { return spdy_headers_; }
+
+    absl::string_view body() { return body_; }
+
+    const std::vector<absl::string_view>& push_urls() { return push_urls_; }
+
+   private:
+    void HandleXOriginalUrl();
+    absl::string_view RemoveScheme(absl::string_view url);
+
+    std::string file_name_;
+    std::string file_contents_;
+    absl::string_view body_;
+    spdy::Http2HeaderBlock spdy_headers_;
+    absl::string_view x_original_url_;
+    std::vector<absl::string_view> push_urls_;
+    std::string host_;
+    std::string path_;
+  };
+
+  QuicMemoryCacheBackend();
+  QuicMemoryCacheBackend(const QuicMemoryCacheBackend&) = delete;
+  QuicMemoryCacheBackend& operator=(const QuicMemoryCacheBackend&) = delete;
+  ~QuicMemoryCacheBackend() override;
+
+  // Retrieve a response from this cache for a given host and path..
+  // If no appropriate response exists, nullptr is returned.
+  const QuicBackendResponse* GetResponse(absl::string_view host,
+                                         absl::string_view path) const;
+
+  // Adds a simple response to the cache.  The response headers will
+  // only contain the "content-length" header with the length of |body|.
+  void AddSimpleResponse(absl::string_view host,
+                         absl::string_view path,
+                         int response_code,
+                         absl::string_view body);
+
+  // Add a simple response to the cache as AddSimpleResponse() does, and add
+  // some server push resources(resource path, corresponding response status and
+  // path) associated with it.
+  // Push resource implicitly come from the same host.
+  // TODO(b/171463363): Remove.
+  void AddSimpleResponseWithServerPushResources(
+      absl::string_view host,
+      absl::string_view path,
+      int response_code,
+      absl::string_view body,
+      std::list<QuicBackendResponse::ServerPushInfo> push_resources);
+
+  // Add a response to the cache.
+  void AddResponse(absl::string_view host,
+                   absl::string_view path,
+                   spdy::Http2HeaderBlock response_headers,
+                   absl::string_view response_body);
+
+  // Add a response, with trailers, to the cache.
+  void AddResponse(absl::string_view host,
+                   absl::string_view path,
+                   spdy::Http2HeaderBlock response_headers,
+                   absl::string_view response_body,
+                   spdy::Http2HeaderBlock response_trailers);
+
+  // Add a response, with 103 Early Hints, to the cache.
+  void AddResponseWithEarlyHints(
+      absl::string_view host,
+      absl::string_view path,
+      spdy::Http2HeaderBlock response_headers,
+      absl::string_view response_body,
+      const std::vector<spdy::Http2HeaderBlock>& early_hints);
+
+  // Simulate a special behavior at a particular path.
+  void AddSpecialResponse(
+      absl::string_view host,
+      absl::string_view path,
+      QuicBackendResponse::SpecialResponseType response_type);
+
+  void AddSpecialResponse(
+      absl::string_view host,
+      absl::string_view path,
+      spdy::Http2HeaderBlock response_headers,
+      absl::string_view response_body,
+      QuicBackendResponse::SpecialResponseType response_type);
+
+  // Sets a default response in case of cache misses.  Takes ownership of
+  // 'response'.
+  void AddDefaultResponse(QuicBackendResponse* response);
+
+  // Once called, URLs which have a numeric path will send a dynamically
+  // generated response of that many bytes.
+  void GenerateDynamicResponses();
+
+  void EnableWebTransport();
+
+  // Find all the server push resources associated with |request_url|.
+  // TODO(b/171463363): Remove.
+  std::list<QuicBackendResponse::ServerPushInfo> GetServerPushResources(
+      std::string request_url);
+
+  // Implements the functions for interface QuicSimpleServerBackend
+  // |cache_cirectory| can be generated using `wget -p --save-headers <url>`.
+  bool InitializeBackend(const std::string& cache_directory) override;
+  bool IsBackendInitialized() const override;
+  void FetchResponseFromBackend(
+      const spdy::Http2HeaderBlock& request_headers,
+      const std::string& request_body,
+      QuicSimpleServerBackend::RequestHandler* quic_stream) override;
+  void CloseBackendResponseStream(
+      QuicSimpleServerBackend::RequestHandler* quic_stream) override;
+  WebTransportResponse ProcessWebTransportRequest(
+      const spdy::Http2HeaderBlock& request_headers,
+      WebTransportSession* session) override;
+  bool SupportsWebTransport() override { return enable_webtransport_; }
+
+ private:
+  void AddResponseImpl(absl::string_view host,
+                       absl::string_view path,
+                       QuicBackendResponse::SpecialResponseType response_type,
+                       spdy::Http2HeaderBlock response_headers,
+                       absl::string_view response_body,
+                       spdy::Http2HeaderBlock response_trailers,
+                       const std::vector<spdy::Http2HeaderBlock>& early_hints);
+
+  std::string GetKey(absl::string_view host, absl::string_view path) const;
+
+  // Add some server push urls with given responses for specified
+  // request if these push resources are not associated with this request yet.
+  // TODO(b/171463363): Remove.
+  void MaybeAddServerPushResources(
+      absl::string_view request_host,
+      absl::string_view request_path,
+      std::list<QuicBackendResponse::ServerPushInfo> push_resources);
+
+  // Check if push resource(push_host/push_path) associated with given request
+  // url already exists in server push map.
+  // TODO(b/171463363): Remove.
+  bool PushResourceExistsInCache(std::string original_request_url,
+                                 QuicBackendResponse::ServerPushInfo resource);
+
+  // Cached responses.
+  absl::flat_hash_map<std::string, std::unique_ptr<QuicBackendResponse>>
+      responses_ QUIC_GUARDED_BY(response_mutex_);
+
+  // The default response for cache misses, if set.
+  std::unique_ptr<QuicBackendResponse> default_response_
+      QUIC_GUARDED_BY(response_mutex_);
+
+  // The generate bytes response, if set.
+  std::unique_ptr<QuicBackendResponse> generate_bytes_response_
+      QUIC_GUARDED_BY(response_mutex_);
+
+  // A map from request URL to associated server push responses (if any).
+  // TODO(b/171463363): Remove.
+  std::multimap<std::string, QuicBackendResponse::ServerPushInfo>
+      server_push_resources_ QUIC_GUARDED_BY(response_mutex_);
+
+  // Protects against concurrent access from test threads setting responses, and
+  // server threads accessing those responses.
+  mutable QuicMutex response_mutex_;
+  bool cache_initialized_;
+
+  bool enable_webtransport_ = false;
+};
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_TOOLS_QUIC_MEMORY_CACHE_BACKEND_H_