cros: Enable WebUILoginView reuse.

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

Index: chrome/browser/chromeos/login/lock/webui_screen_locker.cc
diff --git a/chrome/browser/chromeos/login/lock/webui_screen_locker.cc b/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
index f962b73a247cb015ae509a17767713a93035229c..551f8d0f5fc5a5f3e5c6a8a925fd8d3a6c21a212 100644
--- a/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
+++ b/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
@@ -61,7 +61,8 @@ namespace chromeos {
 // WebUIScreenLocker implementation.
 
 WebUIScreenLocker::WebUIScreenLocker(ScreenLocker* screen_locker)
-    : screen_locker_(screen_locker),
+    : WebUILoginView(WebViewSettings()),
+      screen_locker_(screen_locker),
       network_state_helper_(new login::NetworkStateHelper),
       weak_factory_(this) {
   set_should_emit_login_prompt_visible(false);
@@ -88,7 +89,7 @@ WebUIScreenLocker::~WebUIScreenLocker() {
   }
   // If LockScreen() was called, we need to clear the signin screen handler
   // delegate set in ShowSigninScreen so that it no longer points to us.
-  if (login_display_.get())
+  if (login_display_.get() && GetOobeUI())
     GetOobeUI()->ResetSigninScreenHandlerDelegate();
 
   if (keyboard::KeyboardController::GetInstance() && is_observing_keyboard_) {