Add more string_util functions to base namespace.

net/ftp/ftp_util.cc

Index: net/ftp/ftp_util.cc
diff --git a/net/ftp/ftp_util.cc b/net/ftp/ftp_util.cc
index 11956bac45a8e324933b32cd268aa904cd2c63c0..a653dee8be58b2386bc21127e3dc84acb91c1a6b 100644
--- a/net/ftp/ftp_util.cc
+++ b/net/ftp/ftp_util.cc
@@ -108,12 +108,13 @@ std::string FtpUtil::VMSPathToUnix(const std::string& vms_path) {
   std::string result(vms_path);
   if (vms_path[0] == '[') {
     // It's a relative path.
-    ReplaceFirstSubstringAfterOffset(&result, 0, "[.", std::string());
+    base::ReplaceFirstSubstringAfterOffset(
+        &result, 0, "[.", base::StringPiece());
   } else {
     // It's an absolute path.
     result.insert(0, "/");
-    ReplaceSubstringsAfterOffset(&result, 0, ":[000000]", "/");
-    ReplaceSubstringsAfterOffset(&result, 0, ":[", "/");
+    base::ReplaceSubstringsAfterOffset(&result, 0, ":[000000]", "/");
+    base::ReplaceSubstringsAfterOffset(&result, 0, ":[", "/");
   }
   std::replace(result.begin(), result.end(), '.', '/');
   std::replace(result.begin(), result.end(), ']', '/');