Clarify spdy response header log

gfe-relnote: log-only change in invalid response, not flag protected
PiperOrigin-RevId: 249211241
Change-Id: I9091119ce187d200ed6f7ba55ed868f90a6c00db

quic/tools/quic_spdy_client_base.cc

diff --git a/quic/tools/quic_spdy_client_base.cc b/quic/tools/quic_spdy_client_base.cc
index 3d7ef02..534fdbb 100644
--- a/quic/tools/quic_spdy_client_base.cc
+++ b/quic/tools/quic_spdy_client_base.cc
@@ -76,9 +76,11 @@
   // Store response headers and body.
   if (store_response_) {
     auto status = response_headers.find(":status");
-    if (status == response_headers.end() ||
-        !QuicTextUtils::StringToInt(status->second, &latest_response_code_)) {
-      QUIC_LOG(ERROR) << "Invalid response headers";
+    if (status == response_headers.end()) {
+      QUIC_LOG(ERROR) << "Missing :status response header";
+    } else if (!QuicTextUtils::StringToInt(status->second,
+                                           &latest_response_code_)) {
+      QUIC_LOG(ERROR) << "Invalid :status response header: " << status->second;
     }
     latest_response_headers_ = response_headers.DebugString();
     preliminary_response_headers_ =