Revert of Move JoinString to the base namespace

components/autofill/content/renderer/autofill_agent.cc

 // Copyright 2013 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 "components/autofill/content/renderer/autofill_agent.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/i18n/case_conversion.h"
@@ skipping 485 matching lines @@
     // We want to keep just the leading whitespace.
     for (size_t i = 0; i < last_part.size(); ++i) {
       if (!base::IsUnicodeWhitespace(last_part[i])) {
         last_part = last_part.substr(0, i);
         break;
       }
     }
     last_part.append(suggested_value);
     parts[parts.size() - 1] = last_part;
 
-    new_value = base::JoinString(parts, base::ASCIIToUTF16(","));
+    new_value = JoinString(parts, ',');
   }
   FillFieldWithValue(new_value, input_element);
 }
 
 void AutofillAgent::OnFieldTypePredictionsAvailable(
     const std::vector<FormDataPredictions>& forms) {
   for (size_t i = 0; i < forms.size(); ++i) {
     form_cache_.ShowPredictions(forms[i]);
   }
 }
@@ skipping 286 matching lines @@
 
 void AutofillAgent::LegacyAutofillAgent::OnDestruct() {
   // No-op. Don't delete |this|.
 }
 
 void AutofillAgent::LegacyAutofillAgent::FocusChangeComplete() {
   agent_->FocusChangeComplete();
 }
 
 }  // namespace autofill