Remove wchar/wstring version of StringPrintf.

chrome/common/metrics/experiments_helper.cc

Index: chrome/common/metrics/experiments_helper.cc
diff --git a/chrome/common/metrics/experiments_helper.cc b/chrome/common/metrics/experiments_helper.cc
index 9d0c2cb1201038ca5121ac7c469027f9e4b848ef..7c644cd8dff1846aaa083ed8a1d10c9f2ac3d0d2 100644
--- a/chrome/common/metrics/experiments_helper.cc
+++ b/chrome/common/metrics/experiments_helper.cc
@@ -126,8 +126,8 @@ void SetChildProcessLoggingExperimentList() {
   std::vector<string16> experiment_strings(name_group_ids.size());
   for (size_t i = 0; i < name_group_ids.size(); ++i) {
     // Wish there was a StringPrintf for string16... :-(
-    experiment_strings[i] = WideToUTF16(base::StringPrintf(
-        L"%x-%x", name_group_ids[i].name, name_group_ids[i].group));
+    experiment_strings[i] = ASCIIToUTF16(base::StringPrintf(
+        "%x-%x", name_group_ids[i].name, name_group_ids[i].group));
   }
   child_process_logging::SetExperimentList(experiment_strings);
 }