Modify Autotest API to support views based lockscreen

Bug: 781998
Change-Id: I11a456b1341d044b1370652c337f105e0bef649a
Reviewed-on: https://chromium-review.googlesource.com/803622
Commit-Queue: Xiaoyin Hu <xiaoyinh@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521137}

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

@@ -109,6 +109,7 @@ class ScreenLocker : public AuthStatusConsumer,
   // Returns the default instance if it has been created.
   static ScreenLocker* default_screen_locker() { return screen_locker_; }
 
+  // Returns true if the lock UI has been confirmed as displayed.
   bool locked() const { return locked_; }
 
   // Initialize and show the screen locker.

chrome/browser/extensions/api/autotest_private/autotest_private_api.cc

@@ -109,8 +109,12 @@ ExtensionFunction::ResponseAction AutotestPrivateLoginStatusFunction::Run() {
 #if defined(OS_CHROMEOS)
   const user_manager::UserManager* user_manager =
       user_manager::UserManager::Get();
+
+  // default_screen_locker()->locked() is set when the UI is ready, so this
+  // tells us both views based lockscreen UI and screenlocker are ready.
   const bool is_screen_locked =
-      !!chromeos::ScreenLocker::default_screen_locker();
+      !!chromeos::ScreenLocker::default_screen_locker() &&
+      chromeos::ScreenLocker::default_screen_locker()->locked();
 
   if (user_manager) {
     result->SetBoolean("isLoggedIn", user_manager->IsUserLoggedIn());