cros: Preload and reuse the lock screen across lock sessions

chrome/browser/chromeos/login/lock/webui_screen_locker.h

Index: chrome/browser/chromeos/login/lock/webui_screen_locker.h
diff --git a/chrome/browser/chromeos/login/lock/webui_screen_locker.h b/chrome/browser/chromeos/login/lock/webui_screen_locker.h
index c0d9411a177448e0737a321980329ddbbc4df1d8..2a49acd28292e8d7f4a0a1ae8c30ea6048774dc1 100644
--- a/chrome/browser/chromeos/login/lock/webui_screen_locker.h
+++ b/chrome/browser/chromeos/login/lock/webui_screen_locker.h
@@ -55,6 +55,10 @@ class WebUIScreenLocker : public WebUILoginView,
                           public display::DisplayObserver,
                           public content::WebContentsObserver {
  public:
+  // Returns true if the lock screen should be shared.
+  static bool ShouldShareLockScreen();
+  static void Preload();
+
   explicit WebUIScreenLocker(ScreenLocker* screen_locker);
   ~WebUIScreenLocker() override;