Revert of Move JoinString to the base namespace

chrome/browser/extensions/webstore_installer.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/extensions/webstore_installer.h"
 
 #include <set>
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 199 matching lines @@
   std::vector<std::string> params;
   params.push_back("id=" + extension_id);
   if (!install_source.empty())
     params.push_back("installsource=" + install_source);
   params.push_back("uc");
   std::string url_string = extension_urls::GetWebstoreUpdateUrl().spec();
 
   GURL url(url_string + "?response=redirect&" +
            update_client::UpdateQueryParams::Get(
                update_client::UpdateQueryParams::CRX) +
-           "&x=" + net::EscapeQueryParamValue(base::JoinString(params, "&"),
-                                              true));
+           "&x=" + net::EscapeQueryParamValue(JoinString(params, '&'), true));
   DCHECK(url.is_valid());
 
   return url;
 }
 
 void WebstoreInstaller::Delegate::OnExtensionDownloadStarted(
     const std::string& id,
     content::DownloadItem* item) {
 }
 
@@ skipping 551 matching lines @@
         1,
         kMaxSizeKb,
         kNumBuckets);
   }
   UMA_HISTOGRAM_BOOLEAN(
       "Extensions.WebstoreDownload.InterruptTotalSizeUnknown",
       total_bytes <= 0);
 }
 
 }  // namespace extensions