Issue 5013 - Make parameter const ref when applicable.

test/Prefs.cpp

Index: test/Prefs.cpp
===================================================================
--- a/test/Prefs.cpp
+++ b/test/Prefs.cpp
@@ -32,22 +32,22 @@
     std::shared_ptr<std::istream> Read(const std::string& path) const
     {
       if (path == "prefs.json" && !prefsContents.empty())
         return std::shared_ptr<std::istream>(new std::istringstream(prefsContents));
 
       return LazyFileSystem::Read(path);
     }
 
-    void Write(const std::string& path, std::shared_ptr<std::istream> content)
+    void Write(const std::string& path, const std::istream& content)
     {
       if (path == "prefs.json")
       {
         std::stringstream ss;
-        ss << content->rdbuf();
+        ss << content.rdbuf();
         prefsContents = ss.str();
       }
       else
         LazyFileSystem::Write(path, content);
     }
 
     StatResult Stat(const std::string& path) const
     {
@@ -199,9 +199,9 @@
 
   ASSERT_FALSE(fileSystem->prefsContents.empty());
 
   jsEngine.reset();
   Reset(preconfiguredPrefs);
 
   ASSERT_TRUE(filterEngine->GetPref("suppress_first_run_page")->IsBool());
   ASSERT_FALSE(filterEngine->GetPref("suppress_first_run_page")->AsBool());
-}
+}