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

chrome/browser/profiles/profile_list_desktop_unittest.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/profiles/profile_list_desktop.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 55 matching lines @@
         manager()->profile_info_cache(),
         mock_observer_.get(),
         NULL));
     avatar_menu_->RebuildMenu();
     EXPECT_EQ(0, change_count());
     return avatar_menu_.get();
   }
 
   TestingProfileManager* manager() { return &manager_; }
 
-  void AddOmittedProfile(std::string name) {
+  void AddOmittedProfile(const std::string& name) {
     ProfileInfoCache* cache = manager()->profile_info_cache();
     cache->AddProfileToCache(
         cache->GetUserDataDir().AppendASCII(name), ASCIIToUTF16(name),
         std::string(), base::string16(), 0, "TEST_ID");
   }
 
   int change_count() const { return mock_observer_->change_count(); }
 
  private:
   TestingProfileManager manager_;
@@ skipping 265 matching lines @@
   base::string16 supervised_user_label =
       l10n_util::GetStringUTF16(IDS_LEGACY_SUPERVISED_USER_AVATAR_LABEL);
   const AvatarMenu::Item& item1 = model->GetItemAt(0);
   EXPECT_NE(item1.username, supervised_user_label);
 
   const AvatarMenu::Item& item2 = model->GetItemAt(1);
   EXPECT_EQ(item2.username, supervised_user_label);
 }
 
 }  // namespace