Revert of Move JoinString to the base namespace

chrome/browser/chromeos/preferences_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/preferences.h"
 
 #include "base/json/json_string_value_serializer.h"
 #include "base/prefs/pref_member.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
@@ skipping 326 matching lines @@
     EXPECT_EQ(enabled_extension_imes,
               enabled_extension_imes_syncable_.GetValue());
   }
 
   // Translates engine IDs in a CSV string to input method IDs.
   std::string ToInputMethodIds(std::string value) {
     std::vector<std::string> tokens;
     base::SplitString(value, ',', &tokens);
     std::transform(tokens.begin(), tokens.end(), tokens.begin(),
                    &extension_ime_util::GetInputMethodIDByEngineID);
-    return base::JoinString(tokens, ",");
+    return JoinString(tokens, ',');
   }
 
   StringPrefMember preferred_languages_;
   StringPrefMember preferred_languages_syncable_;
   StringPrefMember preload_engines_;
   StringPrefMember preload_engines_syncable_;
   StringPrefMember enabled_extension_imes_;
   StringPrefMember enabled_extension_imes_syncable_;
 
  private:
@@ skipping 340 matching lines @@
         "Syncable values should have added local values on initialization.");
     ExpectGlobalValues(
         "es,en-US",
         "xkb:es::spa,xkb:us::eng,xkb:ru::rus,xkb:xy::xyz," +
             ToInputMethodIds("xkb:jp::jpn"),
         std::string(kIdentityIMEID) + "," + kUnknownIMEID);
   }
 }
 
 }  // namespace chromeos