Move JoinString to the base namespace

base/test/launcher/test_launcher.cc

Index: base/test/launcher/test_launcher.cc
diff --git a/base/test/launcher/test_launcher.cc b/base/test/launcher/test_launcher.cc
index 2a56b6c09dc7521d51e1d352b516831039c4d57e..7c0bc4e9ed9fa283094c248bd3e7e9afead47e36 100644
--- a/base/test/launcher/test_launcher.cc
+++ b/base/test/launcher/test_launcher.cc
@@ -570,7 +570,7 @@ void TestLauncher::OnTestFinished(const TestResult& result) {
           snippet_lines.begin() + truncated_size);
       snippet_lines.insert(snippet_lines.begin(), "<truncated>");
     }
-    fprintf(stdout, "%s", JoinString(snippet_lines, "\n").c_str());
+    fprintf(stdout, "%s", base::JoinString(snippet_lines, "\n").c_str());
     fflush(stdout);
   }