base: Get rid of 'using' declaration of StringAppendF.

net/tools/hresolv/hresolv.cc

Index: net/tools/hresolv/hresolv.cc
diff --git a/net/tools/hresolv/hresolv.cc b/net/tools/hresolv/hresolv.cc
index b5af4ae439e6d18641c78979dac164662c0def1c..da5c4b00f2e9f747d4061f55780d886bb242f14f 100644
--- a/net/tools/hresolv/hresolv.cc
+++ b/net/tools/hresolv/hresolv.cc
@@ -73,7 +73,7 @@ std::string FormatAddrinfoFlags(int ai_flags) {
     if (!flag_names.empty()) {
       flag_names += "|";
     }
-    StringAppendF(&flag_names, "0x%x", ai_flags);
+    base::StringAppendF(&flag_names, "0x%x", ai_flags);
   }
   return flag_names;
 }
@@ -161,14 +161,15 @@ std::string FormatAddrinfoDetails(const struct addrinfo& ai,
 std::string FormatAddressList(const net::AddressList& address_list,
                               const std::string& host) {
   std::string ret_string;
-  StringAppendF(&ret_string, "AddressList {\n");
-  StringAppendF(&ret_string, "  Host: %s\n", host.c_str());
+  base::StringAppendF(&ret_string, "AddressList {\n");
+  base::StringAppendF(&ret_string, "  Host: %s\n", host.c_str());
   for (const struct addrinfo* it = address_list.head();
        it != NULL;
        it = it->ai_next) {
-    StringAppendF(&ret_string, "%s", FormatAddrinfoDetails(*it, "  ").c_str());
+    base::StringAppendF(&ret_string, "%s",
+                        FormatAddrinfoDetails(*it, "  ").c_str());
   }
-  StringAppendF(&ret_string, "}\n");
+  base::StringAppendF(&ret_string, "}\n");
   return ret_string;
 }