add create_publisher signature which takes just a queue size

rclcpp/include/rclcpp/node.hpp

@@ -92,6 +92,17 @@ public:
   rclcpp::callback_group::CallbackGroup::SharedPtr
   create_callback_group(rclcpp::callback_group::CallbackGroupType group_type);
 
+  /// Create and return a Publisher.
+  /**
+   * \param[in] topic_name The topic for this publisher to publish on.
+   * \param[in] qos_history_depth The depth of the publisher message queue.
+   * \return Shared pointer to the created publisher.
+   */
+  template<typename MessageT>
+  typename rclcpp::publisher::Publisher<MessageT>::SharedPtr
+  create_publisher(
+    const std::string & topic_name, size_t qos_history_depth);
+
   /// Create and return a Publisher.
   /**
    * \param[in] topic_name The topic for this publisher to publish on.

rclcpp/include/rclcpp/node_impl.hpp

@@ -113,6 +113,16 @@ Node::create_callback_group(
   return group;
 }
 
+template<typename MessageT>
+typename rclcpp::publisher::Publisher<MessageT>::SharedPtr
+Node::create_publisher(
+  const std::string & topic_name, size_t qos_history_depth)
+{
+  rmw_qos_profile_t qos = rmw_qos_profile_default;
+  qos.depth = qos_history_depth;
+  return this->create_publisher<MessageT>(topic_name, qos);
+}
+
 template<typename MessageT>
 typename publisher::Publisher<MessageT>::SharedPtr
 Node::create_publisher(