sysprof: add dbus utility

This allows viewing the message contents that were captured in a textview
within the utility pane.

We already limit the max size of a message in the capture file, so
presumably messages are relatively small enough to fit here.

src/libsysprof/sysprof-document-dbus-message.c

@@ -51,6 +51,7 @@ enum {
   PROP_SIGNATURE,
   PROP_SENDER,
   PROP_SERIAL,
+  PROP_STRING,
   N_PROPS
 };
 
@@ -130,6 +131,10 @@ sysprof_document_dbus_message_get_property (GObject    *object,
       g_value_set_string (value, sysprof_document_dbus_message_get_signature (self));
       break;
 
+    case PROP_STRING:
+      g_value_take_string (value, sysprof_document_dbus_message_dup_string (self));
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -214,6 +219,11 @@ sysprof_document_dbus_message_class_init (SysprofDocumentDBusMessageClass *klass
                         0,
                         (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
 
+  properties[PROP_STRING] =
+    g_param_spec_string ("string", NULL, NULL,
+                         NULL,
+                         (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
+
   g_object_class_install_properties (object_class, N_PROPS, properties);
 }
 
@@ -444,3 +454,16 @@ sysprof_document_dbus_message_get_bus_type (SysprofDocumentDBusMessage *self)
 
   return 0;
 }
+
+char *
+sysprof_document_dbus_message_dup_string (SysprofDocumentDBusMessage *self)
+{
+  g_autoptr(GDBusMessage) message = NULL;
+
+  g_return_val_if_fail (SYSPROF_IS_DOCUMENT_DBUS_MESSAGE (self), NULL);
+
+  if (!(message = sysprof_document_dbus_message_dup_message (self)))
+    return NULL;
+
+  return g_dbus_message_print (message, 0);
+}