Issue 5013 - Make parameter const ref when applicable.

test/DefaultFileSystem.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <sstream>
 #include <AdblockPlus.h>
 #include <gtest/gtest.h>
 
 namespace
 {
   const std::string testPath = "libadblockplus-t\xc3\xa4st-file";
 
   void WriteString(AdblockPlus::FileSystem& fileSystem,
                    const std::string& content)
   {
-    std::shared_ptr<std::stringstream> input(new std::stringstream);
-    *input << content;
+    std::stringstream input;
+    input << content;
     fileSystem.Write(testPath, input);
   }
 }
 
 TEST(DefaultFileSystemTest, WriteReadRemove)
 {
   AdblockPlus::DefaultFileSystem fileSystem;
   WriteString(fileSystem, "foo");
   std::stringstream output;
   output << fileSystem.Read(testPath)->rdbuf();
@@ skipping 23 matching lines @@
   const std::string newTestPath = testPath + "-new";
   fileSystem.Move(testPath, newTestPath);
   result = fileSystem.Stat(testPath);
   ASSERT_FALSE(result.exists);
   result = fileSystem.Stat(newTestPath);
   ASSERT_TRUE(result.exists);
   fileSystem.Remove(newTestPath);
   result = fileSystem.Stat(newTestPath);
   ASSERT_FALSE(result.exists);
 }