Cleanup: Pass std::string as const reference from content/

content/browser/fileapi/file_system_dir_url_request_job_unittest.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 "storage/browser/fileapi/file_system_dir_url_request_job.h"
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 263 matching lines @@
     icu::UnicodeString date_ustr(match.group(5, status));
     scoped_ptr<icu::DateFormat> formatter(
         icu::DateFormat::createDateTimeInstance(icu::DateFormat::kShort));
     UErrorCode parse_status = U_ZERO_ERROR;
     UDate udate = formatter->parse(date_ustr, parse_status);
     EXPECT_TRUE(U_SUCCESS(parse_status));
     base::Time date = base::Time::FromJsTime(udate);
     EXPECT_FALSE(date.is_null());
   }
 
-  GURL CreateFileSystemURL(const std::string path) {
+  GURL CreateFileSystemURL(const std::string& path) {
     return GURL(kFileSystemURLPrefix + path);
   }
 
   storage::FileSystemFileUtil* file_util() {
     return file_system_context_->sandbox_delegate()->sync_file_util();
   }
 
   // Put the message loop at the top, so that it's the last thing deleted.
   // Delete all task runner objects before the MessageLoop, to help prevent
   // leaks caused by tasks posted during shutdown.
@@ skipping 155 matching lines @@
   ASSERT_FALSE(request_->status().is_success());
   EXPECT_EQ(net::ERR_FILE_NOT_FOUND, request_->status().error());
 
   ASSERT_FALSE(
       storage::ExternalMountPoints::GetSystemInstance()->RevokeFileSystem(
           kValidExternalMountPoint));
 }
 
 }  // namespace
 }  // namespace content