Patch for MATE Power Manager 1.8.0 to fix backlight brightness reset on login

1004_save-ac-brightness-settings.patch

From: Flos Lonicerae <lonicerae@users.noreply.github.com>
Subject: Save applied AC-power brightness settings for the next start
Bug: https://github.com/mate-desktop/mate-power-manager/issues/76
Bug-Debian: https://bugs.debian.org/785017

--- a/src/gpm-backlight.c
+++ b/src/gpm-backlight.c
@@ -627,9 +627,22 @@
 static void
 brightness_changed_cb (GpmBrightness *brightness, guint percentage, GpmBacklight *backlight)
 {
+	gboolean on_battery;
+
 	/* save the new percentage */
 	backlight->priv->master_percentage = percentage;
 
+	/* if using ac power supply, save the brightness settings */
+	g_object_get (backlight->priv->client,
+		      "on-battery", &on_battery,
+		      NULL);
+
+	egg_debug ("on_battery: %i", on_battery);
+	if (!on_battery) {
+		g_settings_set_double(backlight->priv->settings, GPM_SETTINGS_BRIGHTNESS_AC, percentage*1.0f);
+		egg_debug ("saving brightness for ac supply: %i", percentage);
+	}
+
 	/* we emit a signal for the brightness applet */
 	egg_debug ("emitting brightness-changed : %i", percentage);
 	g_signal_emit (backlight, signals [BRIGHTNESS_CHANGED], 0, percentage);