Stop using SpdySynStreamIR for SPDY 4.

net/spdy/spdy_framer.cc

Index: net/spdy/spdy_framer.cc
diff --git a/net/spdy/spdy_framer.cc b/net/spdy/spdy_framer.cc
index dc7231a0f55bbbc57aae11a0ff7fa09051ff3f3b..34e27a78d735cf46f6ba63a21bf6e149bbe8dbfc 100644
--- a/net/spdy/spdy_framer.cc
+++ b/net/spdy/spdy_framer.cc
@@ -2348,6 +2348,7 @@ SpdySerializedFrame* SpdyFramer::SerializeDataFrameHeaderWithPaddingLengthField(
 
 SpdySerializedFrame* SpdyFramer::SerializeSynStream(
     const SpdySynStreamIR& syn_stream) {
+  DCHECK_GE(SPDY3, protocol_version());
   uint8 flags = 0;
   if (syn_stream.fin()) {
     flags |= CONTROL_FLAG_FIN;
@@ -2356,12 +2357,6 @@ SpdySerializedFrame* SpdyFramer::SerializeSynStream(
     // TODO(hkhalil): invalid for HTTP2.
     flags |= CONTROL_FLAG_UNIDIRECTIONAL;
   }
-  // In SPDY >= 4, SYN_STREAM frames are HEADERS frames, but for now
-  // we never expect to have to overflow into a CONTINUATION frame.
-  if (protocol_version() > SPDY3) {
-    flags |= HEADERS_FLAG_PRIORITY;
-    flags |= HEADERS_FLAG_END_HEADERS;
-  }
 
   // Sanitize priority.
   uint8 priority = syn_stream.priority();
@@ -2371,44 +2366,17 @@ SpdySerializedFrame* SpdyFramer::SerializeSynStream(
   }
 
   // The size of this frame, including variable-length name-value block.
-  size_t size = GetSynStreamMinimumSize();
-
-  string hpack_encoding;
-  if (protocol_version() > SPDY3) {
-    if (enable_compression_) {
-      GetHpackEncoder()->EncodeHeaderSet(
-          syn_stream.name_value_block(), &hpack_encoding);
-    } else {
-      GetHpackEncoder()->EncodeHeaderSetWithoutCompression(
-          syn_stream.name_value_block(), &hpack_encoding);
-    }
-    size += hpack_encoding.size();
-  } else {
-    size += GetSerializedLength(syn_stream.name_value_block());
-  }
+  size_t size = GetSynStreamMinimumSize() +
+      GetSerializedLength(syn_stream.name_value_block());
 
   SpdyFrameBuilder builder(size, protocol_version());
-  if (protocol_version() <= SPDY3) {
-    builder.WriteControlFrameHeader(*this, SYN_STREAM, flags);
-    builder.WriteUInt32(syn_stream.stream_id());
-    builder.WriteUInt32(syn_stream.associated_to_stream_id());
-    builder.WriteUInt8(priority << ((protocol_version() <= SPDY2) ? 6 : 5));
-    builder.WriteUInt8(0);  // Unused byte where credential slot used to be.
-  } else {
-    builder.BeginNewFrame(*this,
-                          HEADERS,
-                          flags,
-                          syn_stream.stream_id());
-    // TODO(jgraettinger): Plumb priorities and stream dependencies.
-    builder.WriteUInt32(0);  // Non-exclusive bit and root stream ID.
-    builder.WriteUInt8(MapPriorityToWeight(priority));
-  }
+  builder.WriteControlFrameHeader(*this, SYN_STREAM, flags);
+  builder.WriteUInt32(syn_stream.stream_id());
+  builder.WriteUInt32(syn_stream.associated_to_stream_id());
+  builder.WriteUInt8(priority << ((protocol_version() <= SPDY2) ? 6 : 5));
+  builder.WriteUInt8(0);  // Unused byte where credential slot used to be.
   DCHECK_EQ(GetSynStreamMinimumSize(), builder.length());
-  if (protocol_version() > SPDY3) {
-    builder.WriteBytes(&hpack_encoding[0], hpack_encoding.size());
-  } else {
-    SerializeNameValueBlock(&builder, syn_stream);
-  }
+  SerializeNameValueBlock(&builder, syn_stream);
 
   if (debug_visitor_) {
     const size_t payload_len =
@@ -2635,7 +2603,7 @@ SpdySerializedFrame* SpdyFramer::SerializeHeaders(
       DLOG(DFATAL) << "Priority out-of-bounds.";
       priority = GetLowestPriority();
     }
-    size += 4;
+    size += 5;
   }
 
   string hpack_encoding;
@@ -2666,11 +2634,6 @@ SpdySerializedFrame* SpdyFramer::SerializeHeaders(
                           HEADERS,
                           flags,
                           headers.stream_id());
-    if (headers.has_priority()) {
-      // TODO(jgraettinger): Plumb priorities and stream dependencies.
-      builder.WriteUInt32(0);  // Non-exclusive bit and root stream ID.
-      builder.WriteUInt8(MapPriorityToWeight(priority));
-    }
   }
   if (protocol_version() <= SPDY2) {
     builder.WriteUInt16(0);  // Unused.
@@ -2678,6 +2641,11 @@ SpdySerializedFrame* SpdyFramer::SerializeHeaders(
   DCHECK_EQ(GetHeadersMinimumSize(), builder.length());
 
   if (protocol_version() > SPDY3) {
+    if (headers.has_priority()) {
+      // TODO(jgraettinger): Plumb priorities and stream dependencies.
+      builder.WriteUInt32(0);  // Non-exclusive bit and root stream ID.
+      builder.WriteUInt8(MapPriorityToWeight(priority));
+    }
     WritePayloadWithContinuation(&builder,
                                  hpack_encoding,
                                  headers.stream_id(),