Move JoinString to the base namespace

chrome/test/chromedriver/chrome_launcher.cc

Index: chrome/test/chromedriver/chrome_launcher.cc
diff --git a/chrome/test/chromedriver/chrome_launcher.cc b/chrome/test/chromedriver/chrome_launcher.cc
index 5a79d678006ab640e204ff690606710cd0fe2ef7..9c35f8f6e35d69b11d53f5ed998ac663c8dcdb0a 100644
--- a/chrome/test/chromedriver/chrome_launcher.cc
+++ b/chrome/test/chromedriver/chrome_launcher.cc
@@ -749,8 +749,8 @@ Status ProcessExtensions(const std::vector<std::string>& extensions,
   }
 
   if (extension_paths.size()) {
-    base::FilePath::StringType extension_paths_value = JoinString(
-        extension_paths, FILE_PATH_LITERAL(','));
+    base::FilePath::StringType extension_paths_value = base::JoinString(
+        extension_paths, base::FilePath::StringType(1, ','));
     UpdateExtensionSwitch(switches, "load-extension", extension_paths_value);
   }
   bg_pages->swap(bg_pages_tmp);