Revert of Move JoinString to the base namespace

components/autofill/content/renderer/password_form_conversion_utils_browsertest.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 "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/content/renderer/password_form_conversion_utils.h"
 #include "components/autofill/core/common/password_form.h"
@@ skipping 251 matching lines @@
       ASSERT_NO_FATAL_FAILURE(LoadHTMLAndConvertForm(html, &password_form));
       ASSERT_TRUE(password_form);
 
       EXPECT_EQ(base::UTF8ToUTF16(cases[i].expected_username_element),
                 password_form->username_element);
 
       if (nonempty_username_fields) {
         EXPECT_EQ(base::UTF8ToUTF16(cases[i].expected_username_value),
                   password_form->username_value);
         EXPECT_EQ(base::UTF8ToUTF16(cases[i].expected_other_possible_usernames),
-                  base::JoinString(password_form->other_possible_usernames,
-                                   base::ASCIIToUTF16("+")));
+                  JoinString(password_form->other_possible_usernames, '+'));
       } else {
         EXPECT_TRUE(password_form->username_value.empty());
         EXPECT_TRUE(password_form->other_possible_usernames.empty());
       }
 
       // Do a basic sanity check that we are still having a password field.
       EXPECT_EQ(base::UTF8ToUTF16("password"), password_form->password_element);
       EXPECT_EQ(base::UTF8ToUTF16("secret"), password_form->password_value);
     }
   }
@@ skipping 409 matching lines @@
 
   scoped_ptr<PasswordForm> login_plus_signup_form;
   ASSERT_NO_FATAL_FAILURE(
       LoadHTMLAndConvertForm(login_plus_signup_html, &login_plus_signup_form));
   ASSERT_TRUE(login_plus_signup_form);
   EXPECT_EQ(PasswordForm::Layout::LAYOUT_LOGIN_AND_SIGNUP,
             login_plus_signup_form->layout);
 }
 
 }  // namespace autofill