Cleanup: Pass std::string as const reference if possible

chrome/browser/chromeos/drive/file_system_util.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/drive/file_system_util.h"
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 62 matching lines @@
             ? chromeos::ProfileHelper::Get()->GetUserByProfile(
                   profile->GetOriginalProfile())
             : NULL;
     if (user)
       id = user->username_hash();
   }
   return GetDriveMountPointPathForUserIdHash(id);
 }
 
 base::FilePath GetDriveMountPointPathForUserIdHash(
-    const std::string user_id_hash) {
+    const std::string& user_id_hash) {
   static const base::FilePath::CharType kSpecialMountPointRoot[] =
       FILE_PATH_LITERAL("/special");
   static const char kDriveMountPointNameBase[] = "drive";
   return base::FilePath(kSpecialMountPointRoot)
       .AppendASCII(net::EscapeQueryParamValue(
           kDriveMountPointNameBase +
               (user_id_hash.empty() ? "" : "-" + user_id_hash),
           false));
 }
 
@@ skipping 155 matching lines @@
   const bool disable_sync_over_celluar =
       profile->GetPrefs()->GetBoolean(prefs::kDisableDriveOverCellular);
 
   if (is_connection_cellular && disable_sync_over_celluar)
     return DRIVE_CONNECTED_METERED;
   return DRIVE_CONNECTED;
 }
 
 }  // namespace util
 }  // namespace drive