Convert //components/prefs from scoped_ptr to std::unique_ptr

components/prefs/pref_member.cc

Index: components/prefs/pref_member.cc
diff --git a/components/prefs/pref_member.cc b/components/prefs/pref_member.cc
index b848d722d1ce27ce4ec8133694f985cb2b3896fa..bfeddcc0c822cda3e93302da30e6b6575994c9a2 100644
--- a/components/prefs/pref_member.cc
+++ b/components/prefs/pref_member.cc
@@ -107,7 +107,7 @@ void PrefMemberBase::Internal::UpdateValue(
     bool is_managed,
     bool is_user_modifiable,
     const base::Closure& callback) const {
-  scoped_ptr<base::Value> value(v);
+  std::unique_ptr<base::Value> value(v);
   base::ScopedClosureRunner closure_runner(callback);
   if (IsOnCorrectThread()) {
     bool rv = UpdateValueInternal(*value);