bluetooth: Create stub manager, adapter and device.

dbus/property.cc

Index: dbus/property.cc
diff --git a/dbus/property.cc b/dbus/property.cc
index e8dfe5d26060e41d287beb85bb007231b5b3941a..9289c8614a62d8ea198c7bd5c93d0ca541ddd228 100644
--- a/dbus/property.cc
+++ b/dbus/property.cc
@@ -29,9 +29,10 @@ void PropertyBase::Init(PropertySet* property_set, const std::string& name) {
 // PropertySet implementation.
 //
 
-PropertySet::PropertySet(ObjectProxy* object_proxy,
-                         const std::string& interface,
-                         PropertyChangedCallback property_changed_callback)
+PropertySet::PropertySet(
+    ObjectProxy* object_proxy,
+    const std::string& interface,
+    const PropertyChangedCallback& property_changed_callback)
     : object_proxy_(object_proxy),
       interface_(interface),
       property_changed_callback_(property_changed_callback),