[sysprof] visualizers: add comment about how to add data visualizers

[Christian Hergert <chergert src gnome org>]

commit fc0eff6d4b66d9968c47f4dd7fa35583145fa014
Author: Christian Hergert <chergert redhat com>
Date:   Sat May 19 13:01:05 2018 +0100

    visualizers: add comment about how to add data visualizers

 lib/visualizers/sp-visualizer-list.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/lib/visualizers/sp-visualizer-list.c b/lib/visualizers/sp-visualizer-list.c
index 675c0e8..5b0c570 100644
--- a/lib/visualizers/sp-visualizer-list.c
+++ b/lib/visualizers/sp-visualizer-list.c
@@ -261,6 +261,14 @@ handle_capture_results (GObject      *object,
 
   state = g_task_get_task_data (G_TASK (result));
 
+  /*
+   * TODO: It would be really nice if we had a more structured way to do this
+   *       so that data collections and visualizations could be mapped
+   *       together. One way to do so might be to create the concept of an
+   *       "instrument" which represents that pair and allows the user to
+   *       select what sort of data collections they'd like to see.
+   */
+
   if (state->has_cpu)
     {
       GtkWidget *row = g_object_new (SP_TYPE_CPU_VISUALIZER_ROW,