Move DNS functions from net_error_info.h into error_page namespace.

components/error_page/renderer/net_error_helper_core_unittest.cc

Index: components/error_page/renderer/net_error_helper_core_unittest.cc
diff --git a/components/error_page/renderer/net_error_helper_core_unittest.cc b/components/error_page/renderer/net_error_helper_core_unittest.cc
index e799512bfdefb72b0e03865b7068e3d424654b71..4721f639b94280590c194c736616079c3e6010ba 100644
--- a/components/error_page/renderer/net_error_helper_core_unittest.cc
+++ b/components/error_page/renderer/net_error_helper_core_unittest.cc
@@ -30,8 +30,6 @@ namespace {
 
 using blink::WebURLError;
 using chrome_common_net::DnsProbeStatus;
-using chrome_common_net::DnsProbeStatusToString;
-using error_page::ErrorPageParams;
 
 const char kFailedUrl[] = "http://failed/";
 const char kFailedHttpsUrl[] = "https://failed/";
@@ -120,8 +118,7 @@ std::string ErrorToString(const WebURLError& error, bool is_failed_post) {
 WebURLError ProbeError(DnsProbeStatus status) {
   WebURLError error;
   error.unreachableURL = GURL(kFailedUrl);
-  error.domain = blink::WebString::fromUTF8(
-      chrome_common_net::kDnsProbeErrorDomain);
+  error.domain = blink::WebString::fromUTF8(kDnsProbeErrorDomain);
   error.reason = status;
   return error;
 }