diff --git a/build/source_list.bzl b/build/source_list.bzl
index e5c653b..9fb34e8 100644
--- a/build/source_list.bzl
+++ b/build/source_list.bzl
@@ -371,6 +371,7 @@
     "spdy/core/hpack/hpack_output_stream.h",
     "spdy/core/hpack/hpack_static_table.h",
     "spdy/core/http2_frame_decoder_adapter.h",
+    "spdy/core/http2_header_block.h",
     "spdy/core/http2_header_block_hpack_listener.h",
     "spdy/core/metadata_extension.h",
     "spdy/core/no_op_headers_handler.h",
@@ -670,12 +671,12 @@
     "spdy/core/hpack/hpack_output_stream.cc",
     "spdy/core/hpack/hpack_static_table.cc",
     "spdy/core/http2_frame_decoder_adapter.cc",
+    "spdy/core/http2_header_block.cc",
     "spdy/core/metadata_extension.cc",
     "spdy/core/recording_headers_handler.cc",
     "spdy/core/spdy_alt_svc_wire_format.cc",
     "spdy/core/spdy_frame_builder.cc",
     "spdy/core/spdy_framer.cc",
-    "spdy/core/spdy_header_block.cc",
     "spdy/core/spdy_header_storage.cc",
     "spdy/core/spdy_no_op_visitor.cc",
     "spdy/core/spdy_pinnable_buffer_piece.cc",
@@ -1266,11 +1267,11 @@
     "spdy/core/hpack/hpack_output_stream_test.cc",
     "spdy/core/hpack/hpack_round_trip_test.cc",
     "spdy/core/hpack/hpack_static_table_test.cc",
+    "spdy/core/http2_header_block_test.cc",
     "spdy/core/metadata_extension_test.cc",
     "spdy/core/spdy_alt_svc_wire_format_test.cc",
     "spdy/core/spdy_frame_builder_test.cc",
     "spdy/core/spdy_framer_test.cc",
-    "spdy/core/spdy_header_block_test.cc",
     "spdy/core/spdy_header_storage_test.cc",
     "spdy/core/spdy_intrusive_list_test.cc",
     "spdy/core/spdy_pinnable_buffer_piece_test.cc",
diff --git a/build/source_list.gni b/build/source_list.gni
index 3deabbd..a89cff2 100644
--- a/build/source_list.gni
+++ b/build/source_list.gni
@@ -371,6 +371,7 @@
     "src/quiche/spdy/core/hpack/hpack_output_stream.h",
     "src/quiche/spdy/core/hpack/hpack_static_table.h",
     "src/quiche/spdy/core/http2_frame_decoder_adapter.h",
+    "src/quiche/spdy/core/http2_header_block.h",
     "src/quiche/spdy/core/http2_header_block_hpack_listener.h",
     "src/quiche/spdy/core/metadata_extension.h",
     "src/quiche/spdy/core/no_op_headers_handler.h",
@@ -670,12 +671,12 @@
     "src/quiche/spdy/core/hpack/hpack_output_stream.cc",
     "src/quiche/spdy/core/hpack/hpack_static_table.cc",
     "src/quiche/spdy/core/http2_frame_decoder_adapter.cc",
+    "src/quiche/spdy/core/http2_header_block.cc",
     "src/quiche/spdy/core/metadata_extension.cc",
     "src/quiche/spdy/core/recording_headers_handler.cc",
     "src/quiche/spdy/core/spdy_alt_svc_wire_format.cc",
     "src/quiche/spdy/core/spdy_frame_builder.cc",
     "src/quiche/spdy/core/spdy_framer.cc",
-    "src/quiche/spdy/core/spdy_header_block.cc",
     "src/quiche/spdy/core/spdy_header_storage.cc",
     "src/quiche/spdy/core/spdy_no_op_visitor.cc",
     "src/quiche/spdy/core/spdy_pinnable_buffer_piece.cc",
@@ -1266,11 +1267,11 @@
     "src/quiche/spdy/core/hpack/hpack_output_stream_test.cc",
     "src/quiche/spdy/core/hpack/hpack_round_trip_test.cc",
     "src/quiche/spdy/core/hpack/hpack_static_table_test.cc",
+    "src/quiche/spdy/core/http2_header_block_test.cc",
     "src/quiche/spdy/core/metadata_extension_test.cc",
     "src/quiche/spdy/core/spdy_alt_svc_wire_format_test.cc",
     "src/quiche/spdy/core/spdy_frame_builder_test.cc",
     "src/quiche/spdy/core/spdy_framer_test.cc",
-    "src/quiche/spdy/core/spdy_header_block_test.cc",
     "src/quiche/spdy/core/spdy_header_storage_test.cc",
     "src/quiche/spdy/core/spdy_intrusive_list_test.cc",
     "src/quiche/spdy/core/spdy_pinnable_buffer_piece_test.cc",
diff --git a/build/source_list.json b/build/source_list.json
index f3ebe33..4d7c2f9 100644
--- a/build/source_list.json
+++ b/build/source_list.json
@@ -370,6 +370,7 @@
     "quiche/spdy/core/hpack/hpack_output_stream.h",
     "quiche/spdy/core/hpack/hpack_static_table.h",
     "quiche/spdy/core/http2_frame_decoder_adapter.h",
+    "quiche/spdy/core/http2_header_block.h",
     "quiche/spdy/core/http2_header_block_hpack_listener.h",
     "quiche/spdy/core/metadata_extension.h",
     "quiche/spdy/core/no_op_headers_handler.h",
@@ -669,12 +670,12 @@
     "quiche/spdy/core/hpack/hpack_output_stream.cc",
     "quiche/spdy/core/hpack/hpack_static_table.cc",
     "quiche/spdy/core/http2_frame_decoder_adapter.cc",
+    "quiche/spdy/core/http2_header_block.cc",
     "quiche/spdy/core/metadata_extension.cc",
     "quiche/spdy/core/recording_headers_handler.cc",
     "quiche/spdy/core/spdy_alt_svc_wire_format.cc",
     "quiche/spdy/core/spdy_frame_builder.cc",
     "quiche/spdy/core/spdy_framer.cc",
-    "quiche/spdy/core/spdy_header_block.cc",
     "quiche/spdy/core/spdy_header_storage.cc",
     "quiche/spdy/core/spdy_no_op_visitor.cc",
     "quiche/spdy/core/spdy_pinnable_buffer_piece.cc",
@@ -1265,11 +1266,11 @@
     "quiche/spdy/core/hpack/hpack_output_stream_test.cc",
     "quiche/spdy/core/hpack/hpack_round_trip_test.cc",
     "quiche/spdy/core/hpack/hpack_static_table_test.cc",
+    "quiche/spdy/core/http2_header_block_test.cc",
     "quiche/spdy/core/metadata_extension_test.cc",
     "quiche/spdy/core/spdy_alt_svc_wire_format_test.cc",
     "quiche/spdy/core/spdy_frame_builder_test.cc",
     "quiche/spdy/core/spdy_framer_test.cc",
-    "quiche/spdy/core/spdy_header_block_test.cc",
     "quiche/spdy/core/spdy_header_storage_test.cc",
     "quiche/spdy/core/spdy_intrusive_list_test.cc",
     "quiche/spdy/core/spdy_pinnable_buffer_piece_test.cc",
diff --git a/quiche/spdy/core/spdy_header_block.cc b/quiche/spdy/core/http2_header_block.cc
similarity index 99%
rename from quiche/spdy/core/spdy_header_block.cc
rename to quiche/spdy/core/http2_header_block.cc
index fe11260..5004ba9 100644
--- a/quiche/spdy/core/spdy_header_block.cc
+++ b/quiche/spdy/core/http2_header_block.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "quiche/spdy/core/spdy_header_block.h"
+#include "quiche/spdy/core/http2_header_block.h"
 
 #include <string.h>
 
diff --git a/quiche/spdy/core/http2_header_block.h b/quiche/spdy/core/http2_header_block.h
new file mode 100644
index 0000000..62e4d1d
--- /dev/null
+++ b/quiche/spdy/core/http2_header_block.h
@@ -0,0 +1,291 @@
+// 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_SPDY_CORE_HTTP2_HEADER_BLOCK_H_
+#define QUICHE_SPDY_CORE_HTTP2_HEADER_BLOCK_H_
+
+#include <stddef.h>
+
+#include <functional>
+#include <list>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "absl/base/attributes.h"
+#include "quiche/common/platform/api/quiche_export.h"
+#include "quiche/common/platform/api/quiche_logging.h"
+#include "quiche/common/quiche_linked_hash_map.h"
+#include "quiche/common/quiche_text_utils.h"
+#include "quiche/spdy/core/spdy_header_storage.h"
+
+namespace spdy {
+
+namespace test {
+class Http2HeaderBlockPeer;
+class ValueProxyPeer;
+}  // namespace test
+
+#ifndef SPDY_HEADER_DEBUG
+#if !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
+#define SPDY_HEADER_DEBUG 1
+#else  // !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
+#define SPDY_HEADER_DEBUG 0
+#endif  // !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
+#endif  // SPDY_HEADER_DEBUG
+
+// This class provides a key-value map that can be used to store SPDY header
+// names and values. This data structure preserves insertion order.
+//
+// Under the hood, this data structure uses large, contiguous blocks of memory
+// to store names and values. Lookups may be performed with absl::string_view
+// keys, and values are returned as absl::string_views (via ValueProxy, below).
+// Value absl::string_views are valid as long as the Http2HeaderBlock exists;
+// allocated memory is never freed until Http2HeaderBlock's destruction.
+//
+// This implementation does not make much of an effort to minimize wasted space.
+// It's expected that keys are rarely deleted from a Http2HeaderBlock.
+class QUICHE_EXPORT_PRIVATE Http2HeaderBlock {
+ private:
+  // Stores a list of value fragments that can be joined later with a
+  // key-dependent separator.
+  class QUICHE_EXPORT_PRIVATE HeaderValue {
+   public:
+    HeaderValue(SpdyHeaderStorage* storage, absl::string_view key,
+                absl::string_view initial_value);
+
+    // Moves are allowed.
+    HeaderValue(HeaderValue&& other);
+    HeaderValue& operator=(HeaderValue&& other);
+
+    void set_storage(SpdyHeaderStorage* storage);
+
+    // Copies are not.
+    HeaderValue(const HeaderValue& other) = delete;
+    HeaderValue& operator=(const HeaderValue& other) = delete;
+
+    ~HeaderValue();
+
+    // Consumes at most |fragment.size()| bytes of memory.
+    void Append(absl::string_view fragment);
+
+    absl::string_view value() const { return as_pair().second; }
+    const std::pair<absl::string_view, absl::string_view>& as_pair() const;
+
+    // Size estimate including separators. Used when keys are erased from
+    // Http2HeaderBlock.
+    size_t SizeEstimate() const { return size_; }
+
+   private:
+    // May allocate a large contiguous region of memory to hold the concatenated
+    // fragments and separators.
+    absl::string_view ConsolidatedValue() const;
+
+    mutable SpdyHeaderStorage* storage_;
+    mutable std::vector<absl::string_view> fragments_;
+    // The first element is the key; the second is the consolidated value.
+    mutable std::pair<absl::string_view, absl::string_view> pair_;
+    size_t size_ = 0;
+    size_t separator_size_ = 0;
+  };
+
+  typedef quiche::QuicheLinkedHashMap<absl::string_view, HeaderValue,
+                                      quiche::StringPieceCaseHash,
+                                      quiche::StringPieceCaseEqual>
+      MapType;
+
+ public:
+  typedef std::pair<absl::string_view, absl::string_view> value_type;
+
+  // Provides iteration over a sequence of std::pair<absl::string_view,
+  // absl::string_view>, even though the underlying MapType::value_type is
+  // different. Dereferencing the iterator will result in memory allocation for
+  // multi-value headers.
+  class QUICHE_EXPORT_PRIVATE iterator {
+   public:
+    // The following type definitions fulfill the requirements for iterator
+    // implementations.
+    typedef std::pair<absl::string_view, absl::string_view> value_type;
+    typedef value_type& reference;
+    typedef value_type* pointer;
+    typedef std::forward_iterator_tag iterator_category;
+    typedef MapType::iterator::difference_type difference_type;
+
+    // In practice, this iterator only offers access to const value_type.
+    typedef const value_type& const_reference;
+    typedef const value_type* const_pointer;
+
+    explicit iterator(MapType::const_iterator it);
+    iterator(const iterator& other);
+    ~iterator();
+
+    // This will result in memory allocation if the value consists of multiple
+    // fragments.
+    const_reference operator*() const {
+#if SPDY_HEADER_DEBUG
+      QUICHE_CHECK(!dereference_forbidden_);
+#endif  // SPDY_HEADER_DEBUG
+      return it_->second.as_pair();
+    }
+
+    const_pointer operator->() const { return &(this->operator*()); }
+    bool operator==(const iterator& it) const { return it_ == it.it_; }
+    bool operator!=(const iterator& it) const { return !(*this == it); }
+
+    iterator& operator++() {
+      it_++;
+      return *this;
+    }
+
+    iterator operator++(int) {
+      auto ret = *this;
+      this->operator++();
+      return ret;
+    }
+
+#if SPDY_HEADER_DEBUG
+    void forbid_dereference() { dereference_forbidden_ = true; }
+#endif  // SPDY_HEADER_DEBUG
+
+   private:
+    MapType::const_iterator it_;
+#if SPDY_HEADER_DEBUG
+    bool dereference_forbidden_ = false;
+#endif  // SPDY_HEADER_DEBUG
+  };
+  typedef iterator const_iterator;
+
+  Http2HeaderBlock();
+  Http2HeaderBlock(const Http2HeaderBlock& other) = delete;
+  Http2HeaderBlock(Http2HeaderBlock&& other);
+  ~Http2HeaderBlock();
+
+  Http2HeaderBlock& operator=(const Http2HeaderBlock& other) = delete;
+  Http2HeaderBlock& operator=(Http2HeaderBlock&& other);
+  Http2HeaderBlock Clone() const;
+
+  bool operator==(const Http2HeaderBlock& other) const;
+  bool operator!=(const Http2HeaderBlock& other) const;
+
+  // Provides a human readable multi-line representation of the stored header
+  // keys and values.
+  std::string DebugString() const;
+
+  iterator begin() { return wrap_iterator(map_.begin()); }
+  iterator end() { return wrap_iterator(map_.end()); }
+  const_iterator begin() const { return wrap_const_iterator(map_.begin()); }
+  const_iterator end() const { return wrap_const_iterator(map_.end()); }
+  bool empty() const { return map_.empty(); }
+  size_t size() const { return map_.size(); }
+  iterator find(absl::string_view key) { return wrap_iterator(map_.find(key)); }
+  const_iterator find(absl::string_view key) const {
+    return wrap_const_iterator(map_.find(key));
+  }
+  bool contains(absl::string_view key) const { return find(key) != end(); }
+  void erase(absl::string_view key);
+
+  // Clears both our MapType member and the memory used to hold headers.
+  void clear();
+
+  // The next few methods copy data into our backing storage.
+
+  // If key already exists in the block, replaces the value of that key. Else
+  // adds a new header to the end of the block.
+  void insert(const value_type& value);
+
+  // If a header with the key is already present, then append the value to the
+  // existing header value, NUL ("\0") separated unless the key is cookie, in
+  // which case the separator is "; ".
+  // If there is no such key, a new header with the key and value is added.
+  void AppendValueOrAddHeader(const absl::string_view key,
+                              const absl::string_view value);
+
+  // This object provides automatic conversions that allow Http2HeaderBlock to
+  // be nearly a drop-in replacement for
+  // SpdyLinkedHashMap<std::string, std::string>.
+  // It reads data from or writes data to a SpdyHeaderStorage.
+  class QUICHE_EXPORT_PRIVATE ValueProxy {
+   public:
+    ~ValueProxy();
+
+    // Moves are allowed.
+    ValueProxy(ValueProxy&& other);
+    ValueProxy& operator=(ValueProxy&& other);
+
+    // Copies are not.
+    ValueProxy(const ValueProxy& other) = delete;
+    ValueProxy& operator=(const ValueProxy& other) = delete;
+
+    // Assignment modifies the underlying Http2HeaderBlock.
+    ValueProxy& operator=(absl::string_view value);
+
+    // Provides easy comparison against absl::string_view.
+    bool operator==(absl::string_view value) const;
+
+    std::string as_string() const;
+
+   private:
+    friend class Http2HeaderBlock;
+    friend class test::ValueProxyPeer;
+
+    ValueProxy(Http2HeaderBlock* block,
+               Http2HeaderBlock::MapType::iterator lookup_result,
+               const absl::string_view key,
+               size_t* spdy_header_block_value_size);
+
+    Http2HeaderBlock* block_;
+    Http2HeaderBlock::MapType::iterator lookup_result_;
+    absl::string_view key_;
+    size_t* spdy_header_block_value_size_;
+    bool valid_;
+  };
+
+  // Allows either lookup or mutation of the value associated with a key.
+  ABSL_MUST_USE_RESULT ValueProxy operator[](const absl::string_view key);
+
+  size_t TotalBytesUsed() const { return key_size_ + value_size_; }
+
+ private:
+  friend class test::Http2HeaderBlockPeer;
+
+  inline iterator wrap_iterator(MapType::const_iterator inner_iterator) const {
+#if SPDY_HEADER_DEBUG
+    iterator outer_iterator(inner_iterator);
+    if (inner_iterator == map_.end()) {
+      outer_iterator.forbid_dereference();
+    }
+    return outer_iterator;
+#else   // SPDY_HEADER_DEBUG
+    return iterator(inner_iterator);
+#endif  // SPDY_HEADER_DEBUG
+  }
+
+  inline const_iterator wrap_const_iterator(
+      MapType::const_iterator inner_iterator) const {
+#if SPDY_HEADER_DEBUG
+    const_iterator outer_iterator(inner_iterator);
+    if (inner_iterator == map_.end()) {
+      outer_iterator.forbid_dereference();
+    }
+    return outer_iterator;
+#else   // SPDY_HEADER_DEBUG
+    return iterator(inner_iterator);
+#endif  // SPDY_HEADER_DEBUG
+  }
+
+  void AppendHeader(const absl::string_view key, const absl::string_view value);
+  absl::string_view WriteKey(const absl::string_view key);
+  size_t bytes_allocated() const;
+
+  // absl::string_views held by |map_| point to memory owned by |storage_|.
+  MapType map_;
+  SpdyHeaderStorage storage_;
+
+  size_t key_size_ = 0;
+  size_t value_size_ = 0;
+};
+
+}  // namespace spdy
+
+#endif  // QUICHE_SPDY_CORE_HTTP2_HEADER_BLOCK_H_
diff --git a/quiche/spdy/core/spdy_header_block_test.cc b/quiche/spdy/core/http2_header_block_test.cc
similarity index 99%
rename from quiche/spdy/core/spdy_header_block_test.cc
rename to quiche/spdy/core/http2_header_block_test.cc
index 6fc604d..4624d7b 100644
--- a/quiche/spdy/core/spdy_header_block_test.cc
+++ b/quiche/spdy/core/http2_header_block_test.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "quiche/spdy/core/spdy_header_block.h"
+#include "quiche/spdy/core/http2_header_block.h"
 
 #include <memory>
 #include <utility>
diff --git a/quiche/spdy/core/spdy_header_block.h b/quiche/spdy/core/spdy_header_block.h
index 21bde19..62c4109 100644
--- a/quiche/spdy/core/spdy_header_block.h
+++ b/quiche/spdy/core/spdy_header_block.h
@@ -5,287 +5,10 @@
 #ifndef QUICHE_SPDY_CORE_SPDY_HEADER_BLOCK_H_
 #define QUICHE_SPDY_CORE_SPDY_HEADER_BLOCK_H_
 
-#include <stddef.h>
-
-#include <functional>
-#include <list>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include "absl/base/attributes.h"
-#include "quiche/common/platform/api/quiche_export.h"
-#include "quiche/common/platform/api/quiche_logging.h"
-#include "quiche/common/quiche_linked_hash_map.h"
-#include "quiche/common/quiche_text_utils.h"
-#include "quiche/spdy/core/spdy_header_storage.h"
+#include "quiche/spdy/core/http2_header_block.h"
 
 namespace spdy {
 
-namespace test {
-class Http2HeaderBlockPeer;
-class ValueProxyPeer;
-}  // namespace test
-
-#ifndef SPDY_HEADER_DEBUG
-#if !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
-#define SPDY_HEADER_DEBUG 1
-#else  // !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
-#define SPDY_HEADER_DEBUG 0
-#endif  // !defined(NDEBUG) || defined(ADDRESS_SANITIZER)
-#endif  // SPDY_HEADER_DEBUG
-
-// This class provides a key-value map that can be used to store SPDY header
-// names and values. This data structure preserves insertion order.
-//
-// Under the hood, this data structure uses large, contiguous blocks of memory
-// to store names and values. Lookups may be performed with absl::string_view
-// keys, and values are returned as absl::string_views (via ValueProxy, below).
-// Value absl::string_views are valid as long as the Http2HeaderBlock exists;
-// allocated memory is never freed until Http2HeaderBlock's destruction.
-//
-// This implementation does not make much of an effort to minimize wasted space.
-// It's expected that keys are rarely deleted from a Http2HeaderBlock.
-class QUICHE_EXPORT_PRIVATE Http2HeaderBlock {
- private:
-  // Stores a list of value fragments that can be joined later with a
-  // key-dependent separator.
-  class QUICHE_EXPORT_PRIVATE HeaderValue {
-   public:
-    HeaderValue(SpdyHeaderStorage* storage, absl::string_view key,
-                absl::string_view initial_value);
-
-    // Moves are allowed.
-    HeaderValue(HeaderValue&& other);
-    HeaderValue& operator=(HeaderValue&& other);
-
-    void set_storage(SpdyHeaderStorage* storage);
-
-    // Copies are not.
-    HeaderValue(const HeaderValue& other) = delete;
-    HeaderValue& operator=(const HeaderValue& other) = delete;
-
-    ~HeaderValue();
-
-    // Consumes at most |fragment.size()| bytes of memory.
-    void Append(absl::string_view fragment);
-
-    absl::string_view value() const { return as_pair().second; }
-    const std::pair<absl::string_view, absl::string_view>& as_pair() const;
-
-    // Size estimate including separators. Used when keys are erased from
-    // Http2HeaderBlock.
-    size_t SizeEstimate() const { return size_; }
-
-   private:
-    // May allocate a large contiguous region of memory to hold the concatenated
-    // fragments and separators.
-    absl::string_view ConsolidatedValue() const;
-
-    mutable SpdyHeaderStorage* storage_;
-    mutable std::vector<absl::string_view> fragments_;
-    // The first element is the key; the second is the consolidated value.
-    mutable std::pair<absl::string_view, absl::string_view> pair_;
-    size_t size_ = 0;
-    size_t separator_size_ = 0;
-  };
-
-  typedef quiche::QuicheLinkedHashMap<absl::string_view, HeaderValue,
-                                      quiche::StringPieceCaseHash,
-                                      quiche::StringPieceCaseEqual>
-      MapType;
-
- public:
-  typedef std::pair<absl::string_view, absl::string_view> value_type;
-
-  // Provides iteration over a sequence of std::pair<absl::string_view,
-  // absl::string_view>, even though the underlying MapType::value_type is
-  // different. Dereferencing the iterator will result in memory allocation for
-  // multi-value headers.
-  class QUICHE_EXPORT_PRIVATE iterator {
-   public:
-    // The following type definitions fulfill the requirements for iterator
-    // implementations.
-    typedef std::pair<absl::string_view, absl::string_view> value_type;
-    typedef value_type& reference;
-    typedef value_type* pointer;
-    typedef std::forward_iterator_tag iterator_category;
-    typedef MapType::iterator::difference_type difference_type;
-
-    // In practice, this iterator only offers access to const value_type.
-    typedef const value_type& const_reference;
-    typedef const value_type* const_pointer;
-
-    explicit iterator(MapType::const_iterator it);
-    iterator(const iterator& other);
-    ~iterator();
-
-    // This will result in memory allocation if the value consists of multiple
-    // fragments.
-    const_reference operator*() const {
-#if SPDY_HEADER_DEBUG
-      QUICHE_CHECK(!dereference_forbidden_);
-#endif  // SPDY_HEADER_DEBUG
-      return it_->second.as_pair();
-    }
-
-    const_pointer operator->() const { return &(this->operator*()); }
-    bool operator==(const iterator& it) const { return it_ == it.it_; }
-    bool operator!=(const iterator& it) const { return !(*this == it); }
-
-    iterator& operator++() {
-      it_++;
-      return *this;
-    }
-
-    iterator operator++(int) {
-      auto ret = *this;
-      this->operator++();
-      return ret;
-    }
-
-#if SPDY_HEADER_DEBUG
-    void forbid_dereference() { dereference_forbidden_ = true; }
-#endif  // SPDY_HEADER_DEBUG
-
-   private:
-    MapType::const_iterator it_;
-#if SPDY_HEADER_DEBUG
-    bool dereference_forbidden_ = false;
-#endif  // SPDY_HEADER_DEBUG
-  };
-  typedef iterator const_iterator;
-
-  Http2HeaderBlock();
-  Http2HeaderBlock(const Http2HeaderBlock& other) = delete;
-  Http2HeaderBlock(Http2HeaderBlock&& other);
-  ~Http2HeaderBlock();
-
-  Http2HeaderBlock& operator=(const Http2HeaderBlock& other) = delete;
-  Http2HeaderBlock& operator=(Http2HeaderBlock&& other);
-  Http2HeaderBlock Clone() const;
-
-  bool operator==(const Http2HeaderBlock& other) const;
-  bool operator!=(const Http2HeaderBlock& other) const;
-
-  // Provides a human readable multi-line representation of the stored header
-  // keys and values.
-  std::string DebugString() const;
-
-  iterator begin() { return wrap_iterator(map_.begin()); }
-  iterator end() { return wrap_iterator(map_.end()); }
-  const_iterator begin() const { return wrap_const_iterator(map_.begin()); }
-  const_iterator end() const { return wrap_const_iterator(map_.end()); }
-  bool empty() const { return map_.empty(); }
-  size_t size() const { return map_.size(); }
-  iterator find(absl::string_view key) { return wrap_iterator(map_.find(key)); }
-  const_iterator find(absl::string_view key) const {
-    return wrap_const_iterator(map_.find(key));
-  }
-  bool contains(absl::string_view key) const { return find(key) != end(); }
-  void erase(absl::string_view key);
-
-  // Clears both our MapType member and the memory used to hold headers.
-  void clear();
-
-  // The next few methods copy data into our backing storage.
-
-  // If key already exists in the block, replaces the value of that key. Else
-  // adds a new header to the end of the block.
-  void insert(const value_type& value);
-
-  // If a header with the key is already present, then append the value to the
-  // existing header value, NUL ("\0") separated unless the key is cookie, in
-  // which case the separator is "; ".
-  // If there is no such key, a new header with the key and value is added.
-  void AppendValueOrAddHeader(const absl::string_view key,
-                              const absl::string_view value);
-
-  // This object provides automatic conversions that allow Http2HeaderBlock to
-  // be nearly a drop-in replacement for
-  // SpdyLinkedHashMap<std::string, std::string>.
-  // It reads data from or writes data to a SpdyHeaderStorage.
-  class QUICHE_EXPORT_PRIVATE ValueProxy {
-   public:
-    ~ValueProxy();
-
-    // Moves are allowed.
-    ValueProxy(ValueProxy&& other);
-    ValueProxy& operator=(ValueProxy&& other);
-
-    // Copies are not.
-    ValueProxy(const ValueProxy& other) = delete;
-    ValueProxy& operator=(const ValueProxy& other) = delete;
-
-    // Assignment modifies the underlying Http2HeaderBlock.
-    ValueProxy& operator=(absl::string_view value);
-
-    // Provides easy comparison against absl::string_view.
-    bool operator==(absl::string_view value) const;
-
-    std::string as_string() const;
-
-   private:
-    friend class Http2HeaderBlock;
-    friend class test::ValueProxyPeer;
-
-    ValueProxy(Http2HeaderBlock* block,
-               Http2HeaderBlock::MapType::iterator lookup_result,
-               const absl::string_view key,
-               size_t* spdy_header_block_value_size);
-
-    Http2HeaderBlock* block_;
-    Http2HeaderBlock::MapType::iterator lookup_result_;
-    absl::string_view key_;
-    size_t* spdy_header_block_value_size_;
-    bool valid_;
-  };
-
-  // Allows either lookup or mutation of the value associated with a key.
-  ABSL_MUST_USE_RESULT ValueProxy operator[](const absl::string_view key);
-
-  size_t TotalBytesUsed() const { return key_size_ + value_size_; }
-
- private:
-  friend class test::Http2HeaderBlockPeer;
-
-  inline iterator wrap_iterator(MapType::const_iterator inner_iterator) const {
-#if SPDY_HEADER_DEBUG
-    iterator outer_iterator(inner_iterator);
-    if (inner_iterator == map_.end()) {
-      outer_iterator.forbid_dereference();
-    }
-    return outer_iterator;
-#else   // SPDY_HEADER_DEBUG
-    return iterator(inner_iterator);
-#endif  // SPDY_HEADER_DEBUG
-  }
-
-  inline const_iterator wrap_const_iterator(
-      MapType::const_iterator inner_iterator) const {
-#if SPDY_HEADER_DEBUG
-    const_iterator outer_iterator(inner_iterator);
-    if (inner_iterator == map_.end()) {
-      outer_iterator.forbid_dereference();
-    }
-    return outer_iterator;
-#else   // SPDY_HEADER_DEBUG
-    return iterator(inner_iterator);
-#endif  // SPDY_HEADER_DEBUG
-  }
-
-  void AppendHeader(const absl::string_view key, const absl::string_view value);
-  absl::string_view WriteKey(const absl::string_view key);
-  size_t bytes_allocated() const;
-
-  // absl::string_views held by |map_| point to memory owned by |storage_|.
-  MapType map_;
-  SpdyHeaderStorage storage_;
-
-  size_t key_size_ = 0;
-  size_t value_size_ = 0;
-};
-
 // TODO(b/156770486): Remove this alias when the rename is complete.
 using SpdyHeaderBlock = Http2HeaderBlock;