[gtk] gdk: Add a private api to find sandboxes

[Matthias Clasen <matthiasc src gnome org>]

commit c83441ae4a55db5487250821eed4a7bf900e495b
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 28 12:04:17 2018 -0400

    gdk: Add a private api to find sandboxes
    
    This will be used in more places in the future.

 gdk/gdk-private.h |  1 +
 gdk/gdk.c         | 14 ++++++++++++++
 2 files changed, 15 insertions(+)
---
diff --git a/gdk/gdk-private.h b/gdk/gdk-private.h
index b4a16c5659..0618f8187f 100644
--- a/gdk/gdk-private.h
+++ b/gdk/gdk-private.h
@@ -39,5 +39,6 @@ void gdk_display_set_double_click_distance (GdkDisplay   *display,
 void gdk_display_set_cursor_theme          (GdkDisplay   *display,
                                             const char   *theme,
                                             int           size);
+gboolean gdk_running_in_sandbox (void);
 
 #endif /* __GDK__PRIVATE_H__ */
diff --git a/gdk/gdk.c b/gdk/gdk.c
index 72d1478f69..b92d374cc9 100644
--- a/gdk/gdk.c
+++ b/gdk/gdk.c
@@ -216,6 +216,19 @@ gdk_display_open_default (void)
   return display;
 }
 
+gboolean
+gdk_running_in_sandbox (void)
+{
+  char *path;
+  gboolean ret;
+
+  path = g_build_filename (g_get_user_runtime_dir (), "flatpak-info", NULL);
+  ret = g_file_test (path, G_FILE_TEST_EXISTS);
+  g_free (path);
+
+  return ret;
+}
+
 /**
  * SECTION:threads
  * @Short_description: Functions for using GDK in multi-threaded programs
@@ -266,3 +279,4 @@ gdk_display_open_default (void)
  * expensive tasks from worker threads, and will handle thread
  * management for you.
  */
+