Move some SpdyHeaderBlock instances from heap to stack.

net/spdy/spdy_http_stream.cc

Index: net/spdy/spdy_http_stream.cc
diff --git a/net/spdy/spdy_http_stream.cc b/net/spdy/spdy_http_stream.cc
index e823675016fbd44eb68014428ad917fb0a8c9e42..25a2501c63e2c53bfffe4b6e9244797751a3057c 100644
--- a/net/spdy/spdy_http_stream.cc
+++ b/net/spdy/spdy_http_stream.cc
@@ -274,12 +274,12 @@ int SpdyHttpStream::SendRequest(const HttpRequestHeaders& request_headers,
     return ERR_IO_PENDING;
   }
 
-  std::unique_ptr<SpdyHeaderBlock> headers(new SpdyHeaderBlock);
+  SpdyHeaderBlock headers;
   CreateSpdyHeadersFromHttpRequest(*request_info_, request_headers, direct_,
-                                   headers.get());
+                                   &headers);
   stream_->net_log().AddEvent(
       NetLog::TYPE_HTTP_TRANSACTION_HTTP2_SEND_REQUEST_HEADERS,
-      base::Bind(&SpdyHeaderBlockNetLogCallback, headers.get()));
+      base::Bind(&SpdyHeaderBlockNetLogCallback, &headers));
   result = stream_->SendRequestHeaders(
       std::move(headers),
       HasUploadData() ? MORE_DATA_TO_SEND : NO_MORE_DATA_TO_SEND);