Bug 1432414 - Use gtk_get_current_event_time() instead of gdk_x11_display_get_user_time() on Wayland, r=jhorak

Emulate what gtk+/gtkwindow.c gtk_window_present_with_time() does - use gdk_x11_display_get_user_time() on X11
and gtk_get_current_event_time() on Wayland to get event timestamp.

MozReview-Commit-ID: GEU6ZrQxq6v

--HG--
extra : rebase_source : db2f3ac03ae4ec9f9c1655cf682bff60a96dd3da

widget/gtk/mozgtk/mozgtk.c

@@ -229,6 +229,7 @@ STUB(gtk_file_filter_new)
 STUB(gtk_file_filter_set_name)
 STUB(gtk_fixed_new)
 STUB(gtk_frame_new)
+STUB(gtk_get_current_event_time)
 STUB(gtk_grab_add)
 STUB(gtk_grab_remove)
 STUB(gtk_handle_box_new)

widget/gtk/nsWindow.cpp

@@ -1363,13 +1363,17 @@ SetUserTimeAndStartupIDForActivatedWindow(GtkWidget* aWindow)
 /* static */ guint32
 nsWindow::GetLastUserInputTime()
 {
-    // gdk_x11_display_get_user_time tracks button and key presses,
-    // DESKTOP_STARTUP_ID used to start the app, drop events from external
-    // drags, WM_DELETE_WINDOW delete events, but not usually mouse motion nor
+    // gdk_x11_display_get_user_time/gtk_get_current_event_time tracks
+    // button and key presses, DESKTOP_STARTUP_ID used to start the app,
+    // drop events from external drags,
+    // WM_DELETE_WINDOW delete events, but not usually mouse motion nor
     // button and key releases.  Therefore use the most recent of
     // gdk_x11_display_get_user_time and the last time that we have seen.
-    guint32 timestamp =
-            gdk_x11_display_get_user_time(gdk_display_get_default());
+    GdkDisplay* gdkDisplay = gdk_display_get_default();
+    guint32 timestamp = GDK_IS_X11_DISPLAY(gdkDisplay) ?
+            gdk_x11_display_get_user_time(gdkDisplay) :
+            gtk_get_current_event_time();
+
     if (sLastUserInputTime != GDK_CURRENT_TIME &&
         TimestampIsNewerThan(sLastUserInputTime, timestamp)) {
         return sLastUserInputTime;