Refactor in preparation for SPDY 4, part 1.

Zero behavioral change to the on-the-wire format nor protocol semantics.

This lands server change 40997047.

Also create spdy_protocol.cc and move some functions to it to
avoid clang warnings.


Review URL: https://chromiumcodereview.appspot.com/12220116

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182053 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 684 insertions, 152 deletions

diff --git a/net/net.gyp b/net/net.gyp
index 51cdaf6..9fad87b 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -826,6 +826,7 @@
         'spdy/spdy_http_utils.h',
         'spdy/spdy_io_buffer.cc',
         'spdy/spdy_io_buffer.h',
+        'spdy/spdy_protocol.cc',
         'spdy/spdy_protocol.h',
         'spdy/spdy_proxy_client_socket.cc',
         'spdy/spdy_proxy_client_socket.h',
diff --git a/net/spdy/spdy_frame_builder.cc b/net/spdy/spdy_frame_builder.cc
index 314dd12..ead527c 100644
--- a/net/spdy/spdy_frame_builder.cc
+++ b/net/spdy/spdy_frame_builder.cc
@@ -12,7 +12,7 @@ namespace net {
 namespace {
 
 // Creates a FlagsAndLength.
-FlagsAndLength CreateFlagsAndLength(SpdyControlFlags flags, size_t length) {
+FlagsAndLength CreateFlagsAndLength(uint8 flags, size_t length) {
   DCHECK_EQ(0u, length & ~static_cast<size_t>(kLengthMask));
   FlagsAndLength flags_length;
   flags_length.length_ = htonl(static_cast<uint32>(length));
@@ -30,7 +30,7 @@ SpdyFrameBuilder::SpdyFrameBuilder(size_t size)
 }
 
 SpdyFrameBuilder::SpdyFrameBuilder(SpdyControlType type,
-                                   SpdyControlFlags flags,
+                                   uint8 flags,
                                    int spdy_version,
                                    size_t size)
     : buffer_(new char[size]),
diff --git a/net/spdy/spdy_frame_builder.h b/net/spdy/spdy_frame_builder.h
index 8f3b0cd..0a2410c 100644
--- a/net/spdy/spdy_frame_builder.h
+++ b/net/spdy/spdy_frame_builder.h
@@ -31,7 +31,9 @@ class NET_EXPORT_PRIVATE SpdyFrameBuilder {
   // Initializes a SpdyFrameBuilder with a buffer of given size,
   // populate with a SPDY control frame header based on
   // |type|, |flags|, and |spdy_version|.
-  SpdyFrameBuilder(SpdyControlType type, SpdyControlFlags flags,
+  //
+  // TODO(akalin): Add a typedef for this uint8.
+  SpdyFrameBuilder(SpdyControlType type, uint8 flags,
                    int spdy_version, size_t size);
 
   // Initiailizes a SpdyFrameBuilder with a buffer of given size,
diff --git a/net/spdy/spdy_framer.cc b/net/spdy/spdy_framer.cc
index 21615a0..96ccf9a 100644
--- a/net/spdy/spdy_framer.cc
+++ b/net/spdy/spdy_framer.cc
@@ -46,6 +46,9 @@ struct DictionaryIds {
 // initialized lazily to avoid static initializers.
 base::LazyInstance<DictionaryIds>::Leaky g_dictionary_ids;
 
+// Used to indicate no flags in a SPDY flags field.
+const uint8 kNoFlags = 0;
+
 }  // namespace
 
 const int SpdyFramer::kMinSpdyVersion = 2;
@@ -677,15 +680,13 @@ void SpdyFramer::WriteHeaderBlock(SpdyFrameBuilder* frame,
   }
   SpdyHeaderBlock::const_iterator it;
   for (it = headers->begin(); it != headers->end(); ++it) {
-    bool wrote_header;
     if (spdy_version < 3) {
-      wrote_header = frame->WriteString(it->first);
-      wrote_header &= frame->WriteString(it->second);
+      frame->WriteString(it->first);
+      frame->WriteString(it->second);
     } else {
-      wrote_header = frame->WriteStringPiece32(it->first);
-      wrote_header &= frame->WriteStringPiece32(it->second);
+      frame->WriteStringPiece32(it->first);
+      frame->WriteStringPiece32(it->second);
     }
-    DCHECK(wrote_header);
   }
 }
 
@@ -1291,29 +1292,20 @@ SpdySynStreamControlFrame* SpdyFramer::CreateSynStream(
     SpdyControlFlags flags,
     bool compressed,
     const SpdyHeaderBlock* headers) {
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
-  DCHECK_EQ(0u, associated_stream_id & ~kStreamIdMask);
-
-  // Find our length.
-  size_t frame_size = SpdySynStreamControlFrame::size() +
-                      GetSerializedLength(spdy_version_, headers);
+  DCHECK_EQ(0, flags & ~CONTROL_FLAG_FIN & ~CONTROL_FLAG_UNIDIRECTIONAL);
 
-  SpdyFrameBuilder frame(SYN_STREAM, flags, spdy_version_, frame_size);
-  frame.WriteUInt32(stream_id);
-  frame.WriteUInt32(associated_stream_id);
-  // Cap as appropriate.
-  if (priority > GetLowestPriority()) {
-    DLOG(DFATAL) << "Priority out-of-bounds.";
-    priority = GetLowestPriority();
-  }
-  // Priority is 2 bits for <spdy3, 3 bits otherwise.
-  frame.WriteUInt8(priority << ((spdy_version_ < 3) ? 6 : 5));
-  frame.WriteUInt8((spdy_version_ < 3) ? 0 : credential_slot);
-  WriteHeaderBlock(&frame, spdy_version_, headers);
-  DCHECK_EQ(frame.length(), frame_size);
+  SpdySynStreamIR syn_stream(stream_id);
+  syn_stream.set_associated_to_stream_id(associated_stream_id);
+  syn_stream.set_priority(priority);
+  syn_stream.set_slot(credential_slot);
+  syn_stream.set_fin((flags & CONTROL_FLAG_FIN) != 0);
+  syn_stream.set_unidirectional((flags & CONTROL_FLAG_UNIDIRECTIONAL) != 0);
+  // TODO(hkhalil): Avoid copy here.
+  *(syn_stream.GetMutableNameValueBlock()) = *headers;
 
   scoped_ptr<SpdySynStreamControlFrame> syn_frame(
-      reinterpret_cast<SpdySynStreamControlFrame*>(frame.take()));
+      reinterpret_cast<SpdySynStreamControlFrame*>(
+          SerializeSynStream(syn_stream)));
   if (compressed) {
     return reinterpret_cast<SpdySynStreamControlFrame*>(
         CompressControlFrame(*syn_frame.get(), headers));
@@ -1321,32 +1313,57 @@ SpdySynStreamControlFrame* SpdyFramer::CreateSynStream(
   return syn_frame.release();
 }
 
+SpdySerializedFrame* SpdyFramer::SerializeSynStream(
+    const SpdySynStreamIR& syn_stream) {
+  uint8 flags = 0;
+  if (syn_stream.fin()) {
+    flags |= CONTROL_FLAG_FIN;
+  }
+  if (syn_stream.unidirectional()) {
+    flags |= CONTROL_FLAG_UNIDIRECTIONAL;
+  }
+
+  // The size, in bytes, of this frame not including the variable-length
+  // name-value block. Calculated as:
+  // 8 (control frame header) + 2 * 4 (stream IDs) + 1 (priority) + 1 (slot)
+  const size_t kSynStreamSizeBeforeNameValueBlock = 18;
+
+  // The size of this frame, including variable-length name-value block.
+  const size_t size = kSynStreamSizeBeforeNameValueBlock
+      + GetSerializedLength(protocol_version(),
+                            &(syn_stream.name_value_block()));
+
+  SpdyFrameBuilder builder(SYN_STREAM, flags, protocol_version(), size);
+  builder.WriteUInt32(syn_stream.stream_id());
+  builder.WriteUInt32(syn_stream.associated_to_stream_id());
+  uint8 priority = syn_stream.priority();
+  if (priority > GetLowestPriority()) {
+    DLOG(DFATAL) << "Priority out-of-bounds.";
+    priority = GetLowestPriority();
+  }
+  builder.WriteUInt8(priority << ((spdy_version_ < 3) ? 6 : 5));
+  builder.WriteUInt8(syn_stream.slot());
+  DCHECK_EQ(kSynStreamSizeBeforeNameValueBlock, builder.length());
+  SerializeNameValueBlock(&builder, syn_stream);
+
+  return builder.take();
+}
+
 SpdySynReplyControlFrame* SpdyFramer::CreateSynReply(
     SpdyStreamId stream_id,
     SpdyControlFlags flags,
     bool compressed,
     const SpdyHeaderBlock* headers) {
-  DCHECK_GT(stream_id, 0u);
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
+  DCHECK_EQ(0, flags & ~CONTROL_FLAG_FIN);
 
-  // Find our length.
-  size_t frame_size = SpdySynReplyControlFrame::size() +
-                      GetSerializedLength(spdy_version_, headers);
-  // In SPDY 2, there were 2 unused bytes before payload.
-  if (spdy_version_ < 3) {
-    frame_size += 2;
-  }
-
-  SpdyFrameBuilder frame(SYN_REPLY, flags, spdy_version_, frame_size);
-  frame.WriteUInt32(stream_id);
-  if (spdy_version_ < 3) {
-    frame.WriteUInt16(0);  // Unused
-  }
-  WriteHeaderBlock(&frame, spdy_version_, headers);
-  DCHECK_EQ(frame.length(), frame_size);
+  SpdySynReplyIR syn_reply(stream_id);
+  syn_reply.set_fin(flags & CONTROL_FLAG_FIN);
+  // TODO(hkhalil): Avoid copy here.
+  *(syn_reply.GetMutableNameValueBlock()) = *headers;
 
   scoped_ptr<SpdySynReplyControlFrame> reply_frame(
-      reinterpret_cast<SpdySynReplyControlFrame*>(frame.take()));
+      reinterpret_cast<SpdySynReplyControlFrame*>(SerializeSynReply(
+          syn_reply)));
   if (compressed) {
     return reinterpret_cast<SpdySynReplyControlFrame*>(
         CompressControlFrame(*reply_frame.get(), headers));
@@ -1354,159 +1371,298 @@ SpdySynReplyControlFrame* SpdyFramer::CreateSynReply(
   return reply_frame.release();
 }
 
+SpdySerializedFrame* SpdyFramer::SerializeSynReply(
+    const SpdySynReplyIR& syn_reply) {
+  uint8 flags = 0;
+  if (syn_reply.fin()) {
+    flags |= CONTROL_FLAG_FIN;
+  }
+
+  // The size, in bytes, of this frame not including the variable-length
+  // name-value block. Calculated as:
+  // 8 (control frame header) + 4 (stream ID)
+  size_t syn_reply_size_before_name_value_block = 12;
+  // In SPDY 2, there were 2 unused bytes before payload.
+  if (protocol_version() < 3) {
+    syn_reply_size_before_name_value_block += 2;
+  }
+
+  // The size of this frame, including variable-length name-value block.
+  size_t size = syn_reply_size_before_name_value_block
+      + GetSerializedLength(protocol_version(),
+                            &(syn_reply.name_value_block()));
+
+  SpdyFrameBuilder builder(SYN_REPLY, flags, protocol_version(), size);
+  builder.WriteUInt32(syn_reply.stream_id());
+  if (protocol_version() < 3) {
+    builder.WriteUInt16(0);  // Unused.
+  }
+  DCHECK_EQ(syn_reply_size_before_name_value_block, builder.length());
+  SerializeNameValueBlock(&builder, syn_reply);
+
+  return builder.take();
+}
+
 SpdyRstStreamControlFrame* SpdyFramer::CreateRstStream(
     SpdyStreamId stream_id,
     SpdyRstStreamStatus status) const {
-  DCHECK_GT(stream_id, 0u);
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
-  DCHECK_NE(status, RST_STREAM_INVALID);
-  DCHECK_LT(status, RST_STREAM_NUM_STATUS_CODES);
-
-  size_t frame_size = SpdyRstStreamControlFrame::size();
-  SpdyFrameBuilder frame(RST_STREAM, CONTROL_FLAG_NONE, spdy_version_,
-                         frame_size);
-  frame.WriteUInt32(stream_id);
-  frame.WriteUInt32(status);
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyRstStreamControlFrame*>(frame.take());
+  SpdyRstStreamIR rst_stream(stream_id, status);
+  return reinterpret_cast<SpdyRstStreamControlFrame*>(
+      SerializeRstStream(rst_stream));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializeRstStream(
+    const SpdyRstStreamIR& rst_stream) const {
+  // Size of our RST_STREAM frame. Calculated as:
+  // 8 (control frame header) + 4 (stream id) + 4 (status code)
+  const size_t kRstStreamFrameSize = 16;
+
+  SpdyFrameBuilder builder(RST_STREAM,
+                           kNoFlags,
+                           protocol_version(),
+                           kRstStreamFrameSize);
+  builder.WriteUInt32(rst_stream.stream_id());
+  builder.WriteUInt32(rst_stream.status());
+  DCHECK_EQ(kRstStreamFrameSize, builder.length());
+  return builder.take();
 }
 
 SpdySettingsControlFrame* SpdyFramer::CreateSettings(
     const SettingsMap& values) const {
-  size_t frame_size = SpdySettingsControlFrame::size() + 8 * values.size();
-  SpdyFrameBuilder frame(SETTINGS, CONTROL_FLAG_NONE, spdy_version_,
-                         frame_size);
-  frame.WriteUInt32(values.size());
+  SpdySettingsIR settings;
   for (SettingsMap::const_iterator it = values.begin();
        it != values.end();
-       it++) {
-    SettingsFlagsAndId flags_and_id(it->second.first, it->first);
-    uint32 id_and_flags_wire = flags_and_id.GetWireFormat(spdy_version_);
-    frame.WriteBytes(&id_and_flags_wire, 4);
-    frame.WriteUInt32(it->second.second);
-  }
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdySettingsControlFrame*>(frame.take());
+       ++it) {
+    settings.AddSetting(it->first,
+                        (it->second.first & SETTINGS_FLAG_PLEASE_PERSIST) != 0,
+                        (it->second.first & SETTINGS_FLAG_PERSISTED) != 0,
+                        it->second.second);
+  }
+  return reinterpret_cast<SpdySettingsControlFrame*>(
+      SerializeSettings(settings));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializeSettings(
+    const SpdySettingsIR& settings) const {
+  uint8 flags = 0;
+  if (settings.clear_settings()) {
+    flags |= SETTINGS_FLAG_CLEAR_PREVIOUSLY_PERSISTED_SETTINGS;
+  }
+  const SpdySettingsIR::ValueMap* values = &(settings.values());
+
+  // Size, in bytes, of this SETTINGS frame not including the IDs and values
+  // from the variable-length value block. Calculated as:
+  // 8 (control frame header) + 4 (number of ID/value pairs)
+  const size_t kSettingsSizeWithoutValues = 12;
+  // Size, in bytes, of this SETTINGS frame.
+  const size_t size = kSettingsSizeWithoutValues + (values->size() * 8);
+
+  SpdyFrameBuilder builder(SETTINGS, flags, protocol_version(), size);
+  builder.WriteUInt32(values->size());
+  DCHECK_EQ(kSettingsSizeWithoutValues, builder.length());
+  for (SpdySettingsIR::ValueMap::const_iterator it = values->begin();
+       it != values->end();
+       ++it) {
+    uint8 setting_flags = 0;
+    if (it->second.persist_value) {
+      setting_flags |= SETTINGS_FLAG_PLEASE_PERSIST;
+    }
+    if (it->second.persisted) {
+      setting_flags |= SETTINGS_FLAG_PERSISTED;
+    }
+    SettingsFlagsAndId flags_and_id(setting_flags, it->first);
+    uint32 id_and_flags_wire = flags_and_id.GetWireFormat(protocol_version());
+    builder.WriteBytes(&id_and_flags_wire, 4);
+    builder.WriteUInt32(it->second.value);
+  }
+  DCHECK_EQ(size, builder.length());
+  return builder.take();
 }
 
 SpdyPingControlFrame* SpdyFramer::CreatePingFrame(uint32 unique_id) const {
-  size_t frame_size = SpdyPingControlFrame::size();
-  SpdyFrameBuilder frame(PING, CONTROL_FLAG_NONE, spdy_version_, frame_size);
-  frame.WriteUInt32(unique_id);
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyPingControlFrame*>(frame.take());
+  SpdyPingIR ping(unique_id);
+  return reinterpret_cast<SpdyPingControlFrame*>(SerializePing(ping));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializePing(const SpdyPingIR& ping) const {
+  // Size, in bytes, of this PING frame. Calculated as:
+  // 8 (control frame header) + 4 (id)
+  const size_t kPingSize = 12;
+  SpdyFrameBuilder builder(PING, 0, protocol_version(), kPingSize);
+  builder.WriteUInt32(ping.id());
+  DCHECK_EQ(kPingSize, builder.length());
+  return builder.take();
 }
 
 SpdyGoAwayControlFrame* SpdyFramer::CreateGoAway(
     SpdyStreamId last_accepted_stream_id,
     SpdyGoAwayStatus status) const {
-  DCHECK_EQ(0u, last_accepted_stream_id & ~kStreamIdMask);
-
-  // SPDY 2 GOAWAY frames are 4 bytes smaller than in SPDY 3. We account for
-  // this difference via a separate offset variable, since
-  // SpdyGoAwayControlFrame::size() returns the SPDY 3 size.
-  const size_t goaway_offset = (protocol_version() < 3) ? 4 : 0;
-  size_t frame_size = SpdyGoAwayControlFrame::size() - goaway_offset;
-  SpdyFrameBuilder frame(GOAWAY, CONTROL_FLAG_NONE, spdy_version_, frame_size);
-  frame.WriteUInt32(last_accepted_stream_id);
+  SpdyGoAwayIR goaway(last_accepted_stream_id, status);
+  return reinterpret_cast<SpdyGoAwayControlFrame*>(SerializeGoAway(goaway));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializeGoAway(
+    const SpdyGoAwayIR& goaway) const {
+  // Size, in bytes, of this GOAWAY frame. Calculated as:
+  // 8 (control frame header) + 4 (last good stream id)
+  size_t size = 12;
+  // SPDY 3+ GOAWAY frames also contain a status.
+  if (protocol_version() >= 3) {
+    size += 4;
+  }
+  SpdyFrameBuilder builder(GOAWAY, 0, protocol_version(), size);
+  builder.WriteUInt32(goaway.last_good_stream_id());
   if (protocol_version() >= 3) {
-    frame.WriteUInt32(status);
+    builder.WriteUInt32(goaway.status());
   }
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyGoAwayControlFrame*>(frame.take());
+  DCHECK_EQ(size, builder.length());
+  return builder.take();
 }
 
 SpdyHeadersControlFrame* SpdyFramer::CreateHeaders(
     SpdyStreamId stream_id,
     SpdyControlFlags flags,
     bool compressed,
-    const SpdyHeaderBlock* headers) {
+    const SpdyHeaderBlock* header_block) {
   // Basically the same as CreateSynReply().
-  DCHECK_GT(stream_id, 0u);
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
-
-  // Find our length.
-  size_t frame_size = SpdyHeadersControlFrame::size() +
-                      GetSerializedLength(spdy_version_, headers);
-  // In SPDY 2, there were 2 unused bytes before payload.
-  if (spdy_version_ < 3) {
-    frame_size += 2;
-  }
+  DCHECK_EQ(0, flags & (!CONTROL_FLAG_FIN));
 
-  SpdyFrameBuilder frame(HEADERS, flags, spdy_version_, frame_size);
-  frame.WriteUInt32(stream_id);
-  if (spdy_version_ < 3) {
-    frame.WriteUInt16(0);  // Unused
-  }
-  WriteHeaderBlock(&frame, spdy_version_, headers);
-  DCHECK_EQ(frame.length(), frame_size);
+  SpdyHeadersIR headers(stream_id);
+  headers.set_fin(flags & CONTROL_FLAG_FIN);
+  // TODO(hkhalil): Avoid copy here.
+  *(headers.GetMutableNameValueBlock()) = *header_block;
 
   scoped_ptr<SpdyHeadersControlFrame> headers_frame(
-      reinterpret_cast<SpdyHeadersControlFrame*>(frame.take()));
+      reinterpret_cast<SpdyHeadersControlFrame*>(SerializeHeaders(headers)));
   if (compressed) {
     return reinterpret_cast<SpdyHeadersControlFrame*>(
-        CompressControlFrame(*headers_frame.get(), headers));
+        CompressControlFrame(*headers_frame.get(),
+                             headers.GetMutableNameValueBlock()));
   }
   return headers_frame.release();
 }
 
+SpdySerializedFrame* SpdyFramer::SerializeHeaders(
+    const SpdyHeadersIR& headers) {
+  uint8 flags = 0;
+  if (headers.fin()) {
+    flags |= CONTROL_FLAG_FIN;
+  }
+
+  // The size, in bytes, of this frame not including the variable-length
+  // name-value block. Calculated as:
+  // 8 (control frame header) + 4 (stream ID)
+  size_t headers_size_before_name_value_block = 12;
+  // In SPDY 2, there were 2 unused bytes before payload.
+  if (protocol_version() < 3) {
+    headers_size_before_name_value_block += 2;
+  }
+
+  // The size of this frame, including variable-length name-value block.
+  size_t size = headers_size_before_name_value_block
+      + GetSerializedLength(protocol_version(),
+                            &(headers.name_value_block()));
+
+  SpdyFrameBuilder builder(HEADERS, flags, protocol_version(), size);
+  builder.WriteUInt32(headers.stream_id());
+  if (protocol_version() < 3) {
+    builder.WriteUInt16(0);  // Unused.
+  }
+  DCHECK_EQ(headers_size_before_name_value_block, builder.length());
+
+  SerializeNameValueBlock(&builder, headers);
+  DCHECK_EQ(size, builder.length());
+
+  return builder.take();
+}
+
 SpdyWindowUpdateControlFrame* SpdyFramer::CreateWindowUpdate(
     SpdyStreamId stream_id,
     uint32 delta_window_size) const {
-  DCHECK_GT(stream_id, 0u);
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
-  DCHECK_GT(delta_window_size, 0u);
-  DCHECK_LE(delta_window_size,
-            static_cast<uint32>(kSpdyStreamMaximumWindowSize));
-
-  size_t frame_size = SpdyWindowUpdateControlFrame::size();
-  SpdyFrameBuilder frame(WINDOW_UPDATE, CONTROL_FLAG_NONE, spdy_version_,
-                         frame_size);
-  frame.WriteUInt32(stream_id);
-  frame.WriteUInt32(delta_window_size);
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyWindowUpdateControlFrame*>(frame.take());
+  SpdyWindowUpdateIR window_update(stream_id, delta_window_size);
+  return reinterpret_cast<SpdyWindowUpdateControlFrame*>(
+      SerializeWindowUpdate(window_update));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializeWindowUpdate(
+    const SpdyWindowUpdateIR& window_update) const {
+  // Size, in bytes, of this WINDOW_UPDATE frame. Calculated as:
+  // 8 (control frame header) + 4 (stream id) + 4 (delta)
+  const size_t kWindowUpdateSize = 16;
+
+  SpdyFrameBuilder builder(WINDOW_UPDATE,
+                           kNoFlags,
+                           protocol_version(),
+                           kWindowUpdateSize);
+  builder.WriteUInt32(window_update.stream_id());
+  builder.WriteUInt32(window_update.delta());
+  DCHECK_EQ(kWindowUpdateSize, builder.length());
+  return builder.take();
 }
 
+// TODO(hkhalil): Gut with SpdyCredential removal.
 SpdyCredentialControlFrame* SpdyFramer::CreateCredentialFrame(
     const SpdyCredential& credential) const {
-  // Calculate the size of the frame by adding the size of the
-  // variable length data to the size of the fixed length data.
-  size_t frame_size =  SpdyCredentialControlFrame::size() +
-      credential.proof.length();
-  DCHECK_EQ(SpdyCredentialControlFrame::size(), 14u);
+  SpdyCredentialIR credential_ir(credential.slot);
+  credential_ir.set_proof(credential.proof);
   for (std::vector<std::string>::const_iterator cert = credential.certs.begin();
        cert != credential.certs.end();
        ++cert) {
-    frame_size += sizeof(uint32);  // size of the cert_length field
-    frame_size += cert->length();     // size of the cert_data field
+    credential_ir.AddCertificate(*cert);
   }
+  return reinterpret_cast<SpdyCredentialControlFrame*>(
+      SerializeCredential(credential_ir));
+}
 
-  SpdyFrameBuilder frame(CREDENTIAL, CONTROL_FLAG_NONE, spdy_version_,
-                         frame_size);
-  frame.WriteUInt16(credential.slot);
-  frame.WriteUInt32(credential.proof.size());
-  frame.WriteBytes(credential.proof.c_str(), credential.proof.size());
-  for (std::vector<std::string>::const_iterator cert = credential.certs.begin();
-       cert != credential.certs.end();
-       ++cert) {
-    frame.WriteUInt32(cert->length());
-    frame.WriteBytes(cert->c_str(), cert->length());
+SpdySerializedFrame* SpdyFramer::SerializeCredential(
+    const SpdyCredentialIR& credential) const {
+  size_t size = 8;  // Room for frame header.
+  size += 2;  // Room for slot.
+  size += 4 + credential.proof().length();  // Room for proof.
+  for (SpdyCredentialIR::CertificateList::const_iterator it =
+       credential.certificates()->begin();
+       it != credential.certificates()->end();
+       ++it) {
+    size += 4 + it->length();  // Room for certificate.
+  }
+
+  SpdyFrameBuilder builder(CREDENTIAL, 0, protocol_version(), size);
+  builder.WriteUInt16(credential.slot());
+  builder.WriteStringPiece32(credential.proof());
+  for (SpdyCredentialIR::CertificateList::const_iterator it =
+       credential.certificates()->begin();
+       it != credential.certificates()->end();
+       ++it) {
+    builder.WriteStringPiece32(*it);
   }
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyCredentialControlFrame*>(frame.take());
+  DCHECK_EQ(size, builder.length());
+  return builder.take();
 }
 
 SpdyDataFrame* SpdyFramer::CreateDataFrame(
-    SpdyStreamId stream_id,
-                                           const char* data,
+    SpdyStreamId stream_id, const char* data,
     uint32 len, SpdyDataFlags flags) const {
-  DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
-  size_t frame_size = SpdyDataFrame::size() + len;
-  SpdyFrameBuilder frame(stream_id, flags, frame_size);
-  frame.WriteBytes(data, len);
-  DCHECK_EQ(frame.length(), frame_size);
-  return reinterpret_cast<SpdyDataFrame*>(frame.take());
+  DCHECK_EQ(0, flags & (!DATA_FLAG_FIN));
+
+  SpdyDataIR data_ir(stream_id, base::StringPiece(data, len));
+  data_ir.set_fin(flags & DATA_FLAG_FIN);
+  return reinterpret_cast<SpdyDataFrame*>(SerializeData(data_ir));
+}
+
+SpdySerializedFrame* SpdyFramer::SerializeData(const SpdyDataIR& data) const {
+  // Size, in bytes, of this DATA frame. Calculated as:
+  // 4 (stream id) + 1 (flags) + 3 (length) + payload length
+  const size_t size = 8 + data.data().length();
+
+  SpdyDataFlags flags = DATA_FLAG_NONE;
+  if (data.fin()) {
+    flags = DATA_FLAG_FIN;
+  }
+
+  SpdyFrameBuilder builder(data.stream_id(), flags, size);
+  builder.WriteBytes(data.data().data(), data.data().length());
+  DCHECK_EQ(size, builder.length());
+  return builder.take();
 }
 
 // The following compression setting are based on Brian Olson's analysis. See
@@ -1912,8 +2068,30 @@ SpdyStreamId SpdyFramer::GetControlFrameStreamId(
   return stream_id;
 }
 
-void SpdyFramer::set_enable_compression(bool value) {
-  enable_compression_ = value;
+void SpdyFramer::SerializeNameValueBlock(
+    SpdyFrameBuilder* builder,
+    const SpdyFrameWithNameValueBlockIR& frame) const {
+  const SpdyNameValueBlock* name_value_block = &(frame.name_value_block());
+
+  // Serialize number of headers.
+  if (protocol_version() < 3) {
+    builder->WriteUInt16(name_value_block->size());
+  } else {
+    builder->WriteUInt32(name_value_block->size());
+  }
+
+  // Serialize each header.
+  for (SpdyHeaderBlock::const_iterator it = name_value_block->begin();
+       it != name_value_block->end();
+       ++it) {
+    if (protocol_version() < 3) {
+      builder->WriteString(it->first);
+      builder->WriteString(it->second);
+    } else {
+      builder->WriteStringPiece32(it->first);
+      builder->WriteStringPiece32(it->second);
+    }
+  }
 }
 
 }  // namespace net
diff --git a/net/spdy/spdy_framer.h b/net/spdy/spdy_framer.h
index a97eddb..436ee6c 100644
--- a/net/spdy/spdy_framer.h
+++ b/net/spdy/spdy_framer.h
@@ -44,6 +44,10 @@ class TestSpdyVisitor;
 
 }  // namespace test
 
+// A datastructure for holding a set of headers from either a
+// SYN_STREAM or SYN_REPLY frame.
+typedef std::map<std::string, std::string> SpdyHeaderBlock;
+
 // A datastructure for holding the ID and flag fields for SETTINGS.
 // Conveniently handles converstion to/from wire format.
 class NET_EXPORT_PRIVATE SettingsFlagsAndId {
@@ -72,6 +76,7 @@ typedef std::pair<SpdySettingsFlags, uint32> SettingsFlagsAndValue;
 typedef std::map<SpdySettingsIds, SettingsFlagsAndValue> SettingsMap;
 
 // A datastrcture for holding the contents of a CREDENTIAL frame.
+// TODO(hkhalil): Remove, use SpdyCredentialIR instead.
 struct NET_EXPORT_PRIVATE SpdyCredential {
   SpdyCredential();
   ~SpdyCredential();
@@ -299,6 +304,7 @@ class NET_EXPORT_PRIVATE SpdyFramer {
                                const SpdyHeaderBlock* headers);
 
   // Retrieve serialized length of SpdyHeaderBlock.
+  // TODO(hkhalil): Change to const reference instead of const pointer.
   static size_t GetSerializedLength(const int spdy_version,
                                     const SpdyHeaderBlock* headers);
 
@@ -360,6 +366,7 @@ class NET_EXPORT_PRIVATE SpdyFramer {
                                              SpdyControlFlags flags,
                                              bool compressed,
                                              const SpdyHeaderBlock* headers);
+  SpdySerializedFrame* SerializeSynStream(const SpdySynStreamIR& syn_stream);
 
   // Create a SpdySynReplyControlFrame.
   // |stream_id| is the stream for this frame.
@@ -371,17 +378,22 @@ class NET_EXPORT_PRIVATE SpdyFramer {
                                            SpdyControlFlags flags,
                                            bool compressed,
                                            const SpdyHeaderBlock* headers);
+  SpdySerializedFrame* SerializeSynReply(const SpdySynReplyIR& syn_reply);
 
   SpdyRstStreamControlFrame* CreateRstStream(SpdyStreamId stream_id,
                                              SpdyRstStreamStatus status) const;
+  SpdySerializedFrame* SerializeRstStream(
+      const SpdyRstStreamIR& rst_stream) const;
 
   // Creates an instance of SpdySettingsControlFrame. The SETTINGS frame is
   // used to communicate name/value pairs relevant to the communication channel.
   SpdySettingsControlFrame* CreateSettings(const SettingsMap& values) const;
+  SpdySerializedFrame* SerializeSettings(const SpdySettingsIR& settings) const;
 
   // Creates an instance of SpdyPingControlFrame. The unique_id is used to
   // identify the ping request/response.
   SpdyPingControlFrame* CreatePingFrame(uint32 unique_id) const;
+  SpdySerializedFrame* SerializePing(const SpdyPingIR& ping) const;
 
   // Creates an instance of SpdyGoAwayControlFrame. The GOAWAY frame is used
   // prior to the shutting down of the TCP connection, and includes the
@@ -389,6 +401,7 @@ class NET_EXPORT_PRIVATE SpdyFramer {
   // to completion.
   SpdyGoAwayControlFrame* CreateGoAway(SpdyStreamId last_accepted_stream_id,
                                        SpdyGoAwayStatus status) const;
+  SpdySerializedFrame* SerializeGoAway(const SpdyGoAwayIR& goaway) const;
 
   // Creates an instance of SpdyHeadersControlFrame. The HEADERS frame is used
   // for sending additional headers outside of a SYN_STREAM/SYN_REPLY. The
@@ -397,18 +410,23 @@ class NET_EXPORT_PRIVATE SpdyFramer {
                                          SpdyControlFlags flags,
                                          bool compressed,
                                          const SpdyHeaderBlock* headers);
+  SpdySerializedFrame* SerializeHeaders(const SpdyHeadersIR& headers);
 
   // Creates an instance of SpdyWindowUpdateControlFrame. The WINDOW_UPDATE
   // frame is used to implement per stream flow control in SPDY.
   SpdyWindowUpdateControlFrame* CreateWindowUpdate(
       SpdyStreamId stream_id,
       uint32 delta_window_size) const;
+  SpdySerializedFrame* SerializeWindowUpdate(
+      const SpdyWindowUpdateIR& window_update) const;
 
   // Creates an instance of SpdyCredentialControlFrame.  The CREDENTIAL
   // frame is used to send a client certificate to the server when
   // request more than one origin are sent over the same SPDY session.
   SpdyCredentialControlFrame* CreateCredentialFrame(
       const SpdyCredential& credential) const;
+  SpdySerializedFrame* SerializeCredential(
+      const SpdyCredentialIR& credential) const;
 
   // Given a SpdySettingsControlFrame, extract the settings.
   // Returns true on successful parse, false otherwise.
@@ -430,6 +448,7 @@ class NET_EXPORT_PRIVATE SpdyFramer {
   //    To mark this frame as the last data frame, enable DATA_FLAG_FIN.
   SpdyDataFrame* CreateDataFrame(SpdyStreamId stream_id, const char* data,
                                  uint32 len, SpdyDataFlags flags) const;
+  SpdySerializedFrame* SerializeData(const SpdyDataIR& data) const;
 
   // NOTES about frame compression.
   // We want spdy to compress headers across the entire session.  As long as
@@ -467,7 +486,9 @@ class NET_EXPORT_PRIVATE SpdyFramer {
       const SpdyControlFrame* control_frame);
 
   // For ease of testing and experimentation we can tweak compression on/off.
-  void set_enable_compression(bool value);
+  void set_enable_compression(bool value) {
+    enable_compression_ = value;
+  }
 
   // Used only in log messages.
   void set_display_protocol(const std::string& protocol) {
@@ -560,6 +581,10 @@ class NET_EXPORT_PRIVATE SpdyFramer {
   void WriteHeaderBlockToZ(const SpdyHeaderBlock* headers,
                            z_stream* out) const;
 
+  void SerializeNameValueBlock(
+      SpdyFrameBuilder* builder,
+      const SpdyFrameWithNameValueBlockIR& frame) const;
+
   // Set the error code and moves the framer into the error state.
   void set_error(SpdyError error);
 
diff --git a/net/spdy/spdy_protocol.cc b/net/spdy/spdy_protocol.cc
new file mode 100644
index 0000000..9a43c0d
--- /dev/null
+++ b/net/spdy/spdy_protocol.cc
@@ -0,0 +1,24 @@
+// 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.
+
+#include "net/spdy/spdy_protocol.h"
+
+namespace net {
+
+SpdyFrameWithNameValueBlockIR::SpdyFrameWithNameValueBlockIR(
+    SpdyStreamId stream_id) : SpdyFrameWithFinIR(stream_id) {}
+
+SpdyFrameWithNameValueBlockIR::~SpdyFrameWithNameValueBlockIR() {}
+
+SpdySettingsIR::SpdySettingsIR() : clear_settings_(false) {}
+
+SpdySettingsIR::~SpdySettingsIR() {}
+
+SpdyCredentialIR::SpdyCredentialIR(int16 slot) {
+  set_slot(slot);
+}
+
+SpdyCredentialIR::~SpdyCredentialIR() {}
+
+}  // namespace
diff --git a/net/spdy/spdy_protocol.h b/net/spdy/spdy_protocol.h
index 0647ea1..e9faa24 100644
--- a/net/spdy/spdy_protocol.h
+++ b/net/spdy/spdy_protocol.h
@@ -8,9 +8,12 @@
 #define NET_SPDY_SPDY_PROTOCOL_H_
 
 #include <limits>
+#include <map>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/string_piece.h"
 #include "base/sys_byteorder.h"
 #include "net/spdy/spdy_bitmasks.h"
 
@@ -355,6 +358,7 @@ const int kV3DictionarySize = arraysize(kV3Dictionary);
 // Note: all protocol data structures are on-the-wire format.  That means that
 //       data is stored in network-normalized order.  Readers must use the
 //       accessors provided or call ntohX() functions.
+// TODO(hkhalil): remove above note.
 
 // Types of Spdy Control Frames.
 enum SpdyControlType {
@@ -445,6 +449,12 @@ typedef uint32 SpdyStreamId;
 // number between 0 and 3.
 typedef uint8 SpdyPriority;
 
+typedef uint8 SpdyCredentialSlot;
+
+typedef std::map<std::string, std::string> SpdyNameValueBlock;
+
+typedef uint32 SpdyPingId;
+
 // -------------------------------------------------------------------------
 // These structures mirror the protocol structure definitions.
 
@@ -532,6 +542,298 @@ struct SpdyWindowUpdateControlFrameBlock : SpdyFrameBlock {
 
 #pragma pack(pop)
 
+class SpdyFrame;
+typedef SpdyFrame SpdySerializedFrame;
+
+class SpdyFramer;
+class SpdyFrameBuilder;
+
+// Intermediate representation for SPDY frames.
+// TODO(hkhalil): Rename this class to SpdyFrame when the existing SpdyFrame is
+// gone.
+class SpdyFrameIR {
+ public:
+  virtual ~SpdyFrameIR() {}
+
+ protected:
+  SpdyFrameIR() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SpdyFrameIR);
+};
+
+// Abstract class intended to be inherited by IRs that have a stream associated
+// to them.
+class SpdyFrameWithStreamIdIR : public SpdyFrameIR {
+ public:
+  virtual ~SpdyFrameWithStreamIdIR() {}
+  SpdyStreamId stream_id() const { return stream_id_; }
+  void set_stream_id(SpdyStreamId stream_id) {
+    // TODO(hkhalil): DCHECK_LT(0u, stream_id);
+    DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
+    stream_id_ = stream_id;
+  }
+
+ protected:
+  explicit SpdyFrameWithStreamIdIR(SpdyStreamId stream_id) {
+    set_stream_id(stream_id);
+  }
+
+ private:
+  SpdyStreamId stream_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithStreamIdIR);
+};
+
+// Abstract class intended to be inherited by IRs that have the option of a FIN
+// flag. Implies SpdyFrameWithStreamIdIR.
+class SpdyFrameWithFinIR : public SpdyFrameWithStreamIdIR {
+ public:
+  virtual ~SpdyFrameWithFinIR() {}
+  bool fin() const { return fin_; }
+  void set_fin(bool fin) { fin_ = fin; }
+
+ protected:
+  explicit SpdyFrameWithFinIR(SpdyStreamId stream_id)
+      : SpdyFrameWithStreamIdIR(stream_id),
+        fin_(false) {}
+
+ private:
+  bool fin_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithFinIR);
+};
+
+// Abstract class intended to be inherited by IRs that contain a name-value
+// block. Implies SpdyFrameWithFinIR.
+class SpdyFrameWithNameValueBlockIR : public SpdyFrameWithFinIR {
+ public:
+  const SpdyNameValueBlock& name_value_block() const {
+    return name_value_block_;
+  }
+  SpdyNameValueBlock* GetMutableNameValueBlock() { return &name_value_block_; }
+
+ protected:
+  explicit SpdyFrameWithNameValueBlockIR(SpdyStreamId stream_id);
+  virtual ~SpdyFrameWithNameValueBlockIR();
+
+ private:
+  SpdyNameValueBlock name_value_block_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithNameValueBlockIR);
+};
+
+class SpdyDataIR : public SpdyFrameWithFinIR {
+ public:
+  SpdyDataIR(SpdyStreamId stream_id, const base::StringPiece& data)
+      : SpdyFrameWithFinIR(stream_id) {
+    set_data(data);
+  }
+  base::StringPiece data() const { return data_; }
+  void set_data(const base::StringPiece& data) { data.CopyToString(&data_); }
+
+ private:
+  std::string data_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyDataIR);
+};
+
+class SpdySynStreamIR : public SpdyFrameWithNameValueBlockIR {
+ public:
+  explicit SpdySynStreamIR(SpdyStreamId stream_id)
+      : SpdyFrameWithNameValueBlockIR(stream_id),
+        associated_to_stream_id_(0),
+        priority_(0),
+        slot_(0),
+        unidirectional_(false) {}
+  SpdyStreamId associated_to_stream_id() const {
+    return associated_to_stream_id_;
+  }
+  void set_associated_to_stream_id(SpdyStreamId stream_id) {
+    associated_to_stream_id_ = stream_id;
+  }
+  SpdyPriority priority() const { return priority_; }
+  void set_priority(SpdyPriority priority) { priority_ = priority; }
+  SpdyCredentialSlot slot() const { return slot_; }
+  void set_slot(SpdyCredentialSlot slot) { slot_ = slot; }
+  bool unidirectional() const { return unidirectional_; }
+  void set_unidirectional(bool unidirectional) {
+    unidirectional_ = unidirectional;
+  }
+
+ private:
+  SpdyStreamId associated_to_stream_id_;
+  SpdyPriority priority_;
+  SpdyCredentialSlot slot_;
+  bool unidirectional_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdySynStreamIR);
+};
+
+class SpdySynReplyIR : public SpdyFrameWithNameValueBlockIR {
+ public:
+  explicit SpdySynReplyIR(SpdyStreamId stream_id)
+      : SpdyFrameWithNameValueBlockIR(stream_id) {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SpdySynReplyIR);
+};
+
+class SpdyRstStreamIR : public SpdyFrameWithStreamIdIR {
+ public:
+  SpdyRstStreamIR(SpdyStreamId stream_id, SpdyRstStreamStatus status)
+      : SpdyFrameWithStreamIdIR(stream_id) {
+    set_status(status);
+  }
+  SpdyRstStreamStatus status() const {
+    return status_;
+  }
+  void set_status(SpdyRstStreamStatus status) {
+    DCHECK_NE(status, RST_STREAM_INVALID);
+    DCHECK_LT(status, RST_STREAM_NUM_STATUS_CODES);
+    status_ = status;
+  }
+
+ private:
+  SpdyRstStreamStatus status_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyRstStreamIR);
+};
+
+class SpdySettingsIR : public SpdyFrameIR {
+ public:
+  // Associates flags with a value.
+  struct Value {
+    Value() : persist_value(false),
+              persisted(false),
+              value(0) {}
+    bool persist_value;
+    bool persisted;
+    int32 value;
+  };
+  typedef std::map<SpdySettingsIds, Value> ValueMap;
+
+  SpdySettingsIR();
+
+  virtual ~SpdySettingsIR();
+
+  // Overwrites as appropriate.
+  const ValueMap& values() const { return values_; }
+  void AddSetting(SpdySettingsIds id,
+                  bool persist_value,
+                  bool persisted,
+                  int32 value) {
+    // TODO(hkhalil): DCHECK_LE(SETTINGS_UPLOAD_BANDWIDTH, id);
+    // TODO(hkhalil): DCHECK_GE(SETTINGS_INITIAL_WINDOW_SIZE, id);
+    values_[id].persist_value = persist_value;
+    values_[id].persisted = persisted;
+    values_[id].value = value;
+  }
+  bool clear_settings() const { return clear_settings_; }
+  void set_clear_settings(bool clear_settings) {
+    clear_settings_ = clear_settings;
+  }
+
+ private:
+  ValueMap values_;
+  bool clear_settings_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdySettingsIR);
+};
+
+class SpdyPingIR : public SpdyFrameIR {
+ public:
+  explicit SpdyPingIR(SpdyPingId id) : id_(id) {}
+  SpdyPingId id() const { return id_; }
+
+ private:
+  SpdyPingId id_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyPingIR);
+};
+
+class SpdyGoAwayIR : public SpdyFrameIR {
+ public:
+  SpdyGoAwayIR(SpdyStreamId last_good_stream_id, SpdyGoAwayStatus status) {
+    set_last_good_stream_id(last_good_stream_id);
+    set_status(status);
+  }
+  SpdyStreamId last_good_stream_id() const { return last_good_stream_id_; }
+  void set_last_good_stream_id(SpdyStreamId last_good_stream_id) {
+    DCHECK_LE(0u, last_good_stream_id);
+    DCHECK_EQ(0u, last_good_stream_id & ~kStreamIdMask);
+    last_good_stream_id_ = last_good_stream_id;
+  }
+  SpdyGoAwayStatus status() const { return status_; }
+  void set_status(SpdyGoAwayStatus status) {
+    // TODO(hkhalil): Check valid ranges of status?
+    status_ = status;
+  }
+
+ private:
+  SpdyStreamId last_good_stream_id_;
+  SpdyGoAwayStatus status_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyGoAwayIR);
+};
+
+class SpdyHeadersIR : public SpdyFrameWithNameValueBlockIR {
+ public:
+  explicit SpdyHeadersIR(SpdyStreamId stream_id)
+      : SpdyFrameWithNameValueBlockIR(stream_id) {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SpdyHeadersIR);
+};
+
+class SpdyWindowUpdateIR : public SpdyFrameWithStreamIdIR {
+ public:
+  SpdyWindowUpdateIR(SpdyStreamId stream_id, int32 delta)
+      : SpdyFrameWithStreamIdIR(stream_id) {
+    set_delta(delta);
+  }
+  int32 delta() const { return delta_; }
+  void set_delta(int32 delta) {
+    DCHECK_LT(0, delta);
+    DCHECK_LE(delta, kSpdyStreamMaximumWindowSize);
+    delta_ = delta;
+  }
+
+ private:
+  int32 delta_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyWindowUpdateIR);
+};
+
+class SpdyCredentialIR : public SpdyFrameIR {
+ public:
+  typedef std::vector<std::string> CertificateList;
+
+  explicit SpdyCredentialIR(int16 slot);
+  virtual ~SpdyCredentialIR();
+
+  int16 slot() const { return slot_; }
+  void set_slot(int16 slot) {
+    // TODO(hkhalil): Verify valid slot range?
+    slot_ = slot;
+  }
+  base::StringPiece proof() const { return proof_; }
+  void set_proof(const base::StringPiece& proof) {
+    proof.CopyToString(&proof_);
+  }
+  const CertificateList* certificates() const { return &certificates_; }
+  void AddCertificate(const base::StringPiece& certificate) {
+    certificates_.push_back(certificate.as_string());
+  }
+
+ private:
+  int16 slot_;
+  std::string proof_;
+  CertificateList certificates_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyCredentialIR);
+};
+
 // -------------------------------------------------------------------------
 // Wrapper classes for various SPDY frames.
 
@@ -731,7 +1033,7 @@ class SpdySynStreamControlFrame : public SpdyControlFrame {
   }
 
   void set_credential_slot(uint8 credential_slot) {
-    DCHECK(version() >= 3);
+    DCHECK_LE(3, version());
     mutable_block()->credential_slot_ = credential_slot;
   }