GTK: Put options dialogs in a different window group.

chrome/browser/gtk/options/content_settings_window_gtk.cc

Index: chrome/browser/gtk/options/content_settings_window_gtk.cc
diff --git a/chrome/browser/gtk/options/content_settings_window_gtk.cc b/chrome/browser/gtk/options/content_settings_window_gtk.cc
index 78e513507e2cc73c37dad2e0353612eb0e501dd1..3ad2a15310fec39c2757a1cc4d1066c19cedd475 100644
--- a/chrome/browser/gtk/options/content_settings_window_gtk.cc
+++ b/chrome/browser/gtk/options/content_settings_window_gtk.cc
@@ -146,11 +146,6 @@ ContentSettingsWindowGtk::~ContentSettingsWindowGtk() {
 
 void ContentSettingsWindowGtk::ShowContentSettingsTab(
     ContentSettingsType page) {
-  if (Browser* b = BrowserList::GetLastActive()) {
-    gtk_util::CenterOverWindow(GTK_WINDOW(dialog_),
-                               b->window()->GetNativeHandle());
-  }
-
   // Bring options window to front if it already existed and isn't already
   // in front
   gtk_window_present_with_time(GTK_WINDOW(dialog_),