[HttpStreamParser]: Flush buffers as soon as request is sent.

net/http/http_stream_parser.h

Index: net/http/http_stream_parser.h
diff --git a/net/http/http_stream_parser.h b/net/http/http_stream_parser.h
index 3a4258ee9f34d0800c2b7c25ae6e8e3e8297e206..a70af6560fd0b283397c7916d2fc44236ba0926e 100644
--- a/net/http/http_stream_parser.h
+++ b/net/http/http_stream_parser.h
@@ -135,6 +135,7 @@ class NET_EXPORT_PRIVATE HttpStreamParser {
     STATE_SEND_BODY,
     STATE_SEND_BODY_COMPLETE,
     STATE_SEND_REQUEST_READ_BODY_COMPLETE,
+    STATE_SEND_REQUEST_COMPLETE,
     STATE_READ_HEADERS,
     STATE_READ_HEADERS_COMPLETE,
     STATE_READ_BODY,
@@ -167,6 +168,7 @@ class NET_EXPORT_PRIVATE HttpStreamParser {
   int DoSendBody();
   int DoSendBodyComplete(int result);
   int DoSendRequestReadBodyComplete(int result);
+  int DoSendRequestComplete(int result);
   int DoReadHeaders();
   int DoReadHeadersComplete(int result);
   int DoReadBody();
@@ -191,6 +193,9 @@ class NET_EXPORT_PRIVATE HttpStreamParser {
   // Uploads statistics about status line compliance with RFC 7230.
   void ValidateStatusLine(const std::string& status_line);
 
+  // Check if buffers used to send the request are empty.
+  bool SendRequestBuffersEmpty();
+
   // Next state of the request, when the current one completes.
   State io_state_;