Stringify network error in HTTP2_STREAM_ERROR.

Change NetLogSpdyStreamErrorCallback() to stringify error.
Example netlog output before this change:

HTTP2_STREAM_ERROR
--> description = "SPDY stream closed with error_code: 2"
--> status = -337
--> stream_id = 59

After this change:

HTTP2_STREAM_ERROR
--> description = "SPDY stream closed with error_code: 2"
--> error = SPDY_PROTOCOL_ERROR
--> stream_id = 59

Change-Id: If58ad76f3b99dde7f22e8bf81c2251f6fba9d2e3
Reviewed-on: https://chromium-review.googlesource.com/594192
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491176}

net/spdy/chromium/spdy_stream.cc

@@ -35,12 +35,12 @@ namespace {
 
 std::unique_ptr<base::Value> NetLogSpdyStreamErrorCallback(
     SpdyStreamId stream_id,
-    int status,
+    int net_error,
     const SpdyString* description,
     NetLogCaptureMode /* capture_mode */) {
   auto dict = base::MakeUnique<base::DictionaryValue>();
   dict->SetInteger("stream_id", static_cast<int>(stream_id));
-  dict->SetInteger("status", status);
+  dict->SetString("net_error", ErrorToShortString(net_error));
   dict->SetString("description", *description);
   return std::move(dict);
 }
@@ -636,10 +636,10 @@ int SpdyStream::OnDataSent(size_t frame_size) {
   }
 }
 
-void SpdyStream::LogStreamError(int status, const SpdyString& description) {
+void SpdyStream::LogStreamError(int error, const SpdyString& description) {
   net_log_.AddEvent(NetLogEventType::HTTP2_STREAM_ERROR,
                     base::Bind(&NetLogSpdyStreamErrorCallback, stream_id_,
-                               status, &description));
+                               error, &description));
 }
 
 void SpdyStream::OnClose(int status) {

net/spdy/chromium/spdy_stream.h

@@ -289,7 +289,7 @@ class NET_EXPORT_PRIVATE SpdyStream {
   void OnClose(int status);
 
   // Called by the SpdySession to log stream related errors.
-  void LogStreamError(int status, const SpdyString& description);
+  void LogStreamError(int error, const SpdyString& description);
 
   // If this stream is active, reset it, and close it otherwise. In
   // either case the stream is deleted.