Add e_activity_get_last_known_text().

Evolution is still occasionally getting stuck on shutdown, and although
the evolution-shell log domain shows debug messages for activities that
are preventing shutdown, they frequently look like this:

(evolution:13534): evolution-shell-DEBUG: 5 active 'mail' activities:
(evolution:13534): evolution-shell-DEBUG: * (no description)
(evolution:13534): evolution-shell-DEBUG: * (no description)
(evolution:13534): evolution-shell-DEBUG: * (no description)
(evolution:13534): evolution-shell-DEBUG: * (no description)
(evolution:13534): evolution-shell-DEBUG: * (no description)

I think the lack of descriptions is from CamelOperations popping all
their pushed messages, which is correct behavior but doesn't help us
debug the problem.

e_activity_get_last_known_text() returns the most recent _non-empty_
text value set on the EActivity.  So our debug message can fall back
to that if the EActivity has no description at shutdown:

(evolution:13534): evolution-shell-DEBUG: * (was "blah, blah, blah")

4 files changed, 40 insertions, 0 deletions

diff --git a/doc/reference/evolution-util/evolution-util-sections.txt b/doc/reference/evolution-util/evolution-util-sections.txt
index 7ea056988f..8e0c917638 100644
--- a/doc/reference/evolution-util/evolution-util-sections.txt
+++ b/doc/reference/evolution-util/evolution-util-sections.txt
@@ -43,6 +43,7 @@ e_activity_get_state
 e_activity_set_state
 e_activity_get_text
 e_activity_set_text
+e_activity_get_last_known_text
 e_activity_handle_cancellation
 <SUBSECTION Standard>
 E_ACTIVITY
diff --git a/e-util/e-activity.c b/e-util/e-activity.c
index 87b84495db..e3beb59eaa 100644
--- a/e-util/e-activity.c
+++ b/e-util/e-activity.c
@@ -37,6 +37,7 @@
 #include <stdarg.h>
 #include <glib/gi18n.h>
 #include <camel/camel.h>
+#include <libedataserver/libedataserver.h>
 
 #include "e-util-enumtypes.h"
 
@@ -51,6 +52,7 @@ struct _EActivityPrivate {
 
 	gchar *icon_name;
 	gchar *text;
+	gchar *last_known_text;
 	gdouble percent;
 
 	/* Whether to emit a runtime warning if we
@@ -214,6 +216,7 @@ activity_finalize (GObject *object)
 
 	g_free (priv->icon_name);
 	g_free (priv->text);
+	g_free (priv->last_known_text);
 
 	/* Chain up to parent's finalize() method. */
 	G_OBJECT_CLASS (e_activity_parent_class)->finalize (object);
@@ -726,6 +729,8 @@ void
 e_activity_set_text (EActivity *activity,
                      const gchar *text)
 {
+	gchar *last_known_text = NULL;
+
 	g_return_if_fail (E_IS_ACTIVITY (activity));
 
 	if (g_strcmp0 (activity->priv->text, text) == 0)
@@ -734,10 +739,37 @@ e_activity_set_text (EActivity *activity,
 	g_free (activity->priv->text);
 	activity->priv->text = g_strdup (text);
 
+	/* See e_activity_get_last_known_text(). */
+	last_known_text = e_util_strdup_strip (text);
+	if (last_known_text != NULL) {
+		g_free (activity->priv->last_known_text);
+		activity->priv->last_known_text = last_known_text;
+	}
+
 	g_object_notify (G_OBJECT (activity), "text");
 }
 
 /**
+ * e_activity_get_last_known_text:
+ * @activity: an #EActivity
+ *
+ * Returns the last non-empty #EActivity:text value, so it's possible to
+ * identify what the @activity <emphasis>was</emphasis> doing even if it
+ * currently has no description.
+ *
+ * Mostly useful for debugging.
+ *
+ * Returns: a descriptive message, or %NULL
+ **/
+const gchar *
+e_activity_get_last_known_text (EActivity *activity)
+{
+	g_return_val_if_fail (E_IS_ACTIVITY (activity), NULL);
+
+	return activity->priv->last_known_text;
+}
+
+/**
  * e_activity_handle_cancellation:
  * @activity: an #EActivity
  * @error: a #GError, or %NULL
diff --git a/e-util/e-activity.h b/e-util/e-activity.h
index 9309fe1fb0..1c2cc4e7d3 100644
--- a/e-util/e-activity.h
+++ b/e-util/e-activity.h
@@ -90,6 +90,7 @@ void		e_activity_set_state		(EActivity *activity,
 const gchar *	e_activity_get_text		(EActivity *activity);
 void		e_activity_set_text		(EActivity *activity,
 						 const gchar *text);
+const gchar *	e_activity_get_last_known_text	(EActivity *activity);
 gboolean	e_activity_handle_cancellation	(EActivity *activity,
 						 const GError *error);
 
diff --git a/shell/e-shell-backend.c b/shell/e-shell-backend.c
index 5f7666b238..e4926c5c0a 100644
--- a/shell/e-shell-backend.c
+++ b/shell/e-shell-backend.c
@@ -105,12 +105,18 @@ shell_backend_debug_list_activities (EShellBackend *shell_backend)
 	for (link = head; link != NULL; link = g_list_next (link)) {
 		EActivity *activity = E_ACTIVITY (link->data);
 		gchar *description;
+		const gchar *was;
 
 		description = e_activity_describe (activity);
+		was = e_activity_get_last_known_text (activity);
+
 		if (description != NULL)
 			g_debug ("* %s", description);
+		else if (was != NULL)
+			g_debug ("* (was \"%s\")", was);
 		else
 			g_debug ("* (no description)");
+
 		g_free (description);
 	}
 }