[geary] Add is_background_service to app as a consistent way to determine this.

[Michael Gratton <mjog src gnome org>]

commit e24db89d104d8870b313c5689a264da29305f369
Author: Michael James Gratton <mike vee net>
Date:   Sat Dec 17 14:26:51 2016 +1100

    Add is_background_service to app as a consistent way to determine this.
    
    * src/client/application/geary-application.vala
      (GearyApplication::is_background_service): New property to provide
      common way to determine if the app is a background service. Rework
      other uses of the command line arg or setting to use this.

 src/client/application/geary-application.vala |   11 +++++++++++
 src/client/application/geary-controller.vala  |    6 ++++--
 src/client/components/main-window.vala        |    3 +--
 3 files changed, 16 insertions(+), 4 deletions(-)
---
diff --git a/src/client/application/geary-application.vala b/src/client/application/geary-application.vala
index 5f5f7b5..1aef984 100644
--- a/src/client/application/geary-application.vala
+++ b/src/client/application/geary-application.vala
@@ -98,6 +98,17 @@ public class GearyApplication : Gtk.Application {
      */
     public Configuration config { get; private set; }
 
+    /**
+     * Determines if Geary configured to run as as a background service.
+     *
+     * If this returns `true`, then the primary application instance
+     * will continue to run in the background after the last window is
+     * closed, instead of existing as usual.
+     */
+    public bool is_background_service {
+        get { return Args.hidden_startup || this.config.startup_notifications; }
+    }
+
     public Gtk.ActionGroup actions {
         get; private set; default = new Gtk.ActionGroup("GearyActionGroup");
     }
diff --git a/src/client/application/geary-controller.vala b/src/client/application/geary-controller.vala
index c7a6fa4..588f1e0 100644
--- a/src/client/application/geary-controller.vala
+++ b/src/client/application/geary-controller.vala
@@ -1276,8 +1276,10 @@ public class GearyController : Geary.BaseObject {
      * Displays the main window if we're ready.  Otherwise does nothing.
      */
     private void display_main_window_if_ready() {
-        if (did_attempt_open_all_accounts() && !upgrade_dialog.visible &&
-            !cancellable_open_account.is_cancelled() && !Args.hidden_startup)
+        if (did_attempt_open_all_accounts() &&
+            !upgrade_dialog.visible &&
+            !cancellable_open_account.is_cancelled() &&
+            !this.application.is_background_service)
             main_window.show_all();
     }
     
diff --git a/src/client/components/main-window.vala b/src/client/components/main-window.vala
index 9f9e723..9cf92b7 100644
--- a/src/client/components/main-window.vala
+++ b/src/client/components/main-window.vala
@@ -375,7 +375,7 @@ public class MainWindow : Gtk.ApplicationWindow {
 
     [GtkCallback]
     private bool on_delete_event() {
-        if (Args.hidden_startup || this.application.config.startup_notifications)
+        if (this.application.is_background_service)
             return hide_on_delete();
 
         this.application.exit();
@@ -383,4 +383,3 @@ public class MainWindow : Gtk.ApplicationWindow {
         return true;
     }
 }
-