Make the dbushelper own its own bus handle.

The dbushelper implements an interface that should not be sdbusplus
specific. By making the implementation own the sdbusplus aspects, an
alternate implementation can be swapped in.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I4109772499421e2e6497a0fcad663ebbd1210a7c
diff --git a/dbus/dbuswrite.hpp b/dbus/dbuswrite.hpp
index 06b7dcc..f890781 100644
--- a/dbus/dbuswrite.hpp
+++ b/dbus/dbuswrite.hpp
@@ -33,7 +33,7 @@
   public:
     static std::unique_ptr<WriteInterface>
         createDbusWrite(const std::string& path, int64_t min, int64_t max,
-                        DbusHelperInterface& helper);
+                        std::unique_ptr<DbusHelperInterface> helper);
 
     DbusWritePercent(const std::string& path, int64_t min, int64_t max,
                      const std::string& connectionName) :
@@ -54,7 +54,7 @@
   public:
     static std::unique_ptr<WriteInterface>
         createDbusWrite(const std::string& path, int64_t min, int64_t max,
-                        DbusHelperInterface& helper);
+                        std::unique_ptr<DbusHelperInterface> helper);
 
     DbusWrite(const std::string& path, int64_t min, int64_t max,
               const std::string& connectionName) :