Move StringToLowerASCII to base namespace

extensions/common/extension.cc

Index: extensions/common/extension.cc
diff --git a/extensions/common/extension.cc b/extensions/common/extension.cc
index 89d50f0e098e248c56fbd382acb83b41f45f72b4..eb912e991d9f2b5c3030f6353219c1d6a468d92c 100644
--- a/extensions/common/extension.cc
+++ b/extensions/common/extension.cc
@@ -141,7 +141,7 @@ bool Extension::IdIsValid(const std::string& id) {
 
   // We only support lowercase IDs, because IDs can be used as URL components
   // (where GURL will lowercase it).
-  std::string temp = StringToLowerASCII(id);
+  std::string temp = base::StringToLowerASCII(id);
   for (size_t i = 0; i < temp.size(); i++)
     if (temp[i] < 'a' || temp[i] > 'p')
       return false;