Initialize OOBE/login WebUI in hidden state in parallel with wallpaper animation.

chrome/browser/chromeos/login/webui_login_view.h

Index: chrome/browser/chromeos/login/webui_login_view.h
diff --git a/chrome/browser/chromeos/login/webui_login_view.h b/chrome/browser/chromeos/login/webui_login_view.h
index 0e958f875f0a6c023b78f1c8fa1f216183efb148..86ef94ef8bce5e322ab59b0ef97060da0c93b74d 100644
--- a/chrome/browser/chromeos/login/webui_login_view.h
+++ b/chrome/browser/chromeos/login/webui_login_view.h
@@ -70,6 +70,11 @@ class WebUILoginView : public views::WidgetDelegateView,
   // Opens proxy settings dialog.
   void OpenProxySettings();
 
+  // Called when WebUI is being shown after being initilized hidden.
+  void OnPostponedShow();
+
+  void set_is_hidden(bool hidden) { is_hidden_ = hidden; }
+
   // Toggles status area visibility.
   void SetStatusAreaVisible(bool visible);
 
@@ -140,6 +145,15 @@ class WebUILoginView : public views::WidgetDelegateView,
   // Whether the host window is frozen.
   bool host_window_frozen_;
 
+  // True when WebUI is being initialized hidden.
+  bool is_hidden_;
+
+  // True when NOTIFICATION_LOGIN_WEBUI_VISIBLE notification has fired.
+  bool login_visible_notification_fired_;
+
+  // True is login-prompt-visible event has been already handled.
+  bool login_prompt_visible_handled_;
+
   // Should we emit the login-prompt-visible signal when the login page is
   // displayed?
   bool should_emit_login_prompt_visible_;