Add Net.WebSocket.ResponseCode and ErrorCodes UMA

net/websockets/websocket_basic_handshake_stream.cc

Index: net/websockets/websocket_basic_handshake_stream.cc
diff --git a/net/websockets/websocket_basic_handshake_stream.cc b/net/websockets/websocket_basic_handshake_stream.cc
index a4a634e038bb703eadd207a7eb422e79b0015caf..779b65fb49eb78218a852dc76e19aef134536b2e 100644
--- a/net/websockets/websocket_basic_handshake_stream.cc
+++ b/net/websockets/websocket_basic_handshake_stream.cc
@@ -28,6 +28,7 @@
 #include "net/http/http_response_headers.h"
 #include "net/http/http_status_code.h"
 #include "net/http/http_stream_parser.h"
+#include "net/http/http_util.h"
 #include "net/socket/client_socket_handle.h"
 #include "net/websockets/websocket_basic_stream.h"
 #include "net/websockets/websocket_deflate_predictor.h"
@@ -552,9 +553,18 @@ void WebSocketBasicHandshakeStream::OnFinishOpeningHandshake() {
 
 int WebSocketBasicHandshakeStream::ValidateResponse(int rv) {
   DCHECK(http_response_info_);
-  const HttpResponseHeaders* headers = http_response_info_->headers.get();
+  // Most net errors happen during connection, so they are not seen by this
+  // method. The histogram for error codes is created in
+  // Delegate::OnResponseStarted in websocket_stream.cc instead.
   if (rv >= 0) {
-    switch (headers->response_code()) {
+    const HttpResponseHeaders* headers = http_response_info_->headers.get();
+    const int response_code = headers->response_code();
+    UMA_HISTOGRAM_CUSTOM_ENUMERATION(

[Alexei Svitkine (slow), 2014/06/17 15:34:27]

Use UMA_HISTOGRAM_SPARSE_SLOWLY() here too. It's more efficient than
UMA_HISTOGRAM_CUSTOM_ENUMERATION().

[Adam Rice, 2014/06/18 01:23:19]

Done.

+      "Net.WebSocket.ResponseCode",
+      HttpUtil::MapStatusCodeForHistogram(response_code),
+      // The third argument is only evaluated once.
+      HttpUtil::GetStatusCodesForHistogram());
+    switch (response_code) {
       case HTTP_SWITCHING_PROTOCOLS:
         OnFinishOpeningHandshake();
         return ValidateUpgradeResponse(headers);