Move StartsWith[ASCII] to base namespace.

ui/oobe/oobe_md_ui.cc

Index: ui/oobe/oobe_md_ui.cc
diff --git a/ui/oobe/oobe_md_ui.cc b/ui/oobe/oobe_md_ui.cc
index 07e91b59931d1ded0a1e93c3eaacce06526bfa37..cb86c93baac3036b550446b7e00412fd83d7c75c 100644
--- a/ui/oobe/oobe_md_ui.cc
+++ b/ui/oobe/oobe_md_ui.cc
@@ -21,7 +21,7 @@ void SetUpDataSource(content::WebUIDataSource* source) {
   const size_t prefix_length = arraysize(prefix) - 1;
   for (size_t i = 0; i < kOobeResourcesSize; ++i) {
     std::string name = kOobeResources[i].name;
-    DCHECK(StartsWithASCII(name, prefix, true));
+    DCHECK(base::StartsWithASCII(name, prefix, true));
     source->AddResourcePath(name.substr(prefix_length),
                             kOobeResources[i].value);
   }