net: Append base:: in the StringPrintf calls.

net/base/host_resolver_impl_unittest.cc

Index: net/base/host_resolver_impl_unittest.cc
diff --git a/net/base/host_resolver_impl_unittest.cc b/net/base/host_resolver_impl_unittest.cc
index 233ee211ff5159d8234fce7beac7816aa46f436f..4b28b8c396628e48a9af97055b4cd9b9eec23b5b 100644
--- a/net/base/host_resolver_impl_unittest.cc
+++ b/net/base/host_resolver_impl_unittest.cc
@@ -10,6 +10,7 @@
 #include "base/message_loop.h"
 #include "base/ref_counted.h"
 #include "base/string_util.h"
+#include "base/stringprintf.h"
 #include "net/base/address_list.h"
 #include "net/base/completion_callback.h"
 #include "net/base/mock_host_resolver.h"
@@ -137,7 +138,7 @@ class EchoingHostResolverProc : public HostResolverProc {
                       AddressList* addrlist,
                       int* os_error) {
     // Encode the request's hostname and address_family in the output address.
-    std::string ip_literal = StringPrintf("192.%d.%d.%d",
+    std::string ip_literal = base::StringPrintf("192.%d.%d.%d",
         static_cast<int>(hostname.size()),
         static_cast<int>(hostname[0]),
         static_cast<int>(address_family));