Adding user into session doesn't generate login-prompt-visible.

TEST=manually
BUG=240739

Review URL: https://chromiumcodereview.appspot.com/15700014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@204029 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/login_display_host_impl.cc

@@ -408,6 +408,8 @@ void LoginDisplayHostImpl::StartUserAdding(
   LOG(INFO) << "Login WebUI >> user adding";
   if (!login_window_)
     LoadURL(GURL(kUserAddingURL));
+  // We should emit this signal only at login screen (after reboot or sign out).
+  login_view_->set_should_emit_login_prompt_visible(false);
 
   // Lock container can be transparent after lock screen animation.
   aura::Window* lock_container = ash::Shell::GetContainer(

chrome/browser/chromeos/login/webui_login_view.h

@@ -101,12 +101,12 @@ class WebUILoginView : public views::View,
 
   void set_is_hidden(bool hidden) { is_hidden_ = hidden; }
 
- protected:
-  // Let non-login derived classes suppress emission of this signal.
+  // Let suppress emission of this signal.
   void set_should_emit_login_prompt_visible(bool emit) {
     should_emit_login_prompt_visible_ = emit;
   }
 
+ protected:
   // Overridden from views::View:
   virtual void Layout() OVERRIDE;
   virtual void OnLocaleChanged() OVERRIDE;