Add metrics for DHCP WPAD feature.

net/base/net_errors.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/net_errors.h"
 
 #include "base/basictypes.h"
+#include "base/metrics/histogram.h"
 #include "base/stringize_macros.h"
 
+namespace {
+
+// Get all valid error codes into an array as positive numbers, for use in the
+// |GetAllErrorCodesForUma| function below.
+#define NET_ERROR(label, value) -(value),
+const int kAllErrorCodes[] = {
+#include "net/base/net_error_list.h"
+};
+#undef NET_ERROR
+
+}  // namespace
+
 namespace net {
 
 const char kErrorDomain[] = "net";
 
 const char* ErrorToString(int error) {
   if (error == 0)
     return "net::OK";
 
   switch (error) {
 #define NET_ERROR(label, value) \
   case ERR_ ## label: \
     return "net::" STRINGIZE_NO_EXPANSION(ERR_ ## label);
 #include "net/base/net_error_list.h"
 #undef NET_ERROR
   default:
     return "net::<unknown>";
   }
 }
 
+std::vector<int> GetAllErrorCodesForUma() {
+  return base::CustomHistogram::ArrayToCustomRanges(
+      kAllErrorCodes, arraysize(kAllErrorCodes));
+}
+
 }  // namespace net