Implement auto-login for ARC kiosk.

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index aa925f092d9c0d85b4e70aa20a0aabb2d00a0fb9..b1adcd3781cd3f2f9f08877a260135d5ff3323e2 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -548,6 +548,8 @@ void GaiaScreenHandler::HandleGaiaUIReady() {
 
   if (test_expects_complete_login_)
     SubmitLoginFormForTest();
+  if (Delegate())
+    Delegate()->OnSigninScreenReady();

[Alexander Alekseev, 2016/11/17 22:49:33]

This looks strange. Why do you need this?

[Sergey Poromov, 2016/11/17 22:55:34]

This is needed to notify ExistingUserController that signin screen is ready and
it can auto-launch ARC kiosk session.
This is done similar to public session that wait for the same signal, but from
SigninScreenHandler.
The other solution could be to create separate path of notifying
ExistingUserController, but this will produce several intermediate methods.

[Nikita (slow), 2016/11/18 15:12:58]

Why this change?

[Sergey Poromov, 2016/11/18 15:47:26]

Changed to OnGaiaScreenReady as for auto login it should be reported that GAIA
UI is loaded.

 }
 
 void GaiaScreenHandler::DoCompleteLogin(const std::string& gaia_id,