base: Use std::move() instead of Pass() for real movable types.

base/prefs/pref_value_map.cc

Index: base/prefs/pref_value_map.cc
diff --git a/base/prefs/pref_value_map.cc b/base/prefs/pref_value_map.cc
index 93eadb72db46920b6bc4602b9a02c76e3df4998b..2340e3c273d4771f35ad4373229dc64a6dd14acf 100644
--- a/base/prefs/pref_value_map.cc
+++ b/base/prefs/pref_value_map.cc
@@ -5,6 +5,7 @@
 #include "base/prefs/pref_value_map.h"
 
 #include <map>
+#include <utility>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -40,7 +41,7 @@ bool PrefValueMap::SetValue(const std::string& key,
   if (old_value && value->Equals(old_value))
     return false;
 
-  prefs_.set(key, value.Pass());
+  prefs_.set(key, std::move(value));
   return true;
 }