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

components/search_engines/default_search_manager_unittest.cc

 // Copyright 2014 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/files/scoped_temp_dir.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
@@ skipping 100 matching lines @@
     encodings->AppendString(*it);
   }
   entry->Set(DefaultSearchManager::kInputEncodings, encodings.release());
 
   entry->SetString(DefaultSearchManager::kSearchTermsReplacementKey,
                    data->search_terms_replacement_key);
   entry->SetBoolean(DefaultSearchManager::kDisabledByPolicy, !enabled);
   prefs->SetManagedPref(kDefaultSearchProviderData, entry.release());
 }
 
-scoped_ptr<TemplateURLData> GenerateDummyTemplateURLData(std::string type) {
+scoped_ptr<TemplateURLData> GenerateDummyTemplateURLData(
+    const std::string& type) {
   scoped_ptr<TemplateURLData> data(new TemplateURLData());
   data->SetShortName(base::UTF8ToUTF16(std::string(type).append("name")));
   data->SetKeyword(base::UTF8ToUTF16(std::string(type).append("key")));
   data->SetURL(std::string("http://").append(type).append("foo/{searchTerms}"));
   data->suggestions_url = std::string("http://").append(type).append("sugg");
   data->alternate_urls.push_back(
       std::string("http://").append(type).append("foo/alt"));
   data->favicon_url = GURL("http://icon1");
   data->safe_for_autoreplace = true;
   data->show_in_default_list = true;
@@ skipping 185 matching lines @@
 
   ExpectSimilar(extension_data_3.get(),
                 manager.GetDefaultSearchEngine(&source));
   EXPECT_EQ(DefaultSearchManager::FROM_EXTENSION, source);
 
   manager.ClearExtensionControlledDefaultSearchEngine();
 
   ExpectSimilar(data.get(), manager.GetDefaultSearchEngine(&source));
   EXPECT_EQ(DefaultSearchManager::FROM_USER, source);
 }