Wait for Cryptohome service to be available on login.

chrome/browser/chromeos/login/existing_user_controller.cc

Index: chrome/browser/chromeos/login/existing_user_controller.cc
diff --git a/chrome/browser/chromeos/login/existing_user_controller.cc b/chrome/browser/chromeos/login/existing_user_controller.cc
index 4847d9a76509e89444c00580d41bceafd12776c0..b85c771644435e1ebaf7363776ff70e6a8fa1d30 100644
--- a/chrome/browser/chromeos/login/existing_user_controller.cc
+++ b/chrome/browser/chromeos/login/existing_user_controller.cc
@@ -1238,6 +1238,16 @@ void ExistingUserController::PerformLoginFinishedActions(
     StartAutoLoginTimer();
 }
 
+void ExistingUserController::ContinueLoginWhenCryptohomeAvailable(
+    const base::Closure& continuation,
+    bool service_is_available) {
+  if (!service_is_available) {
+    login_display_->SetUIEnabled(true);

[xiyuan, 2017/04/13 18:07:31]

How about do

  LOG(ERROR) << "Cryptohome service is not available";
  OnAuthFailure(AuthFailure::COULD_NOT_MOUNT_CRYPTOHOME);

so that we get it in log and user gets some visual feedback?

[Sergey Poromov, 2017/04/18 12:50:56]

Done.

+    return;
+  }
+  continuation.Run();
+}
+
 void ExistingUserController::ContinueLoginIfDeviceNotDisabled(
     const base::Closure& continuation) {
   // Disable clicking on other windows and status tray.
@@ -1283,7 +1293,11 @@ void ExistingUserController::ContinueLoginIfDeviceNotDisabled(
     return;
   }
 
-  continuation.Run();
+  chromeos::DBusThreadManager::Get()
+      ->GetCryptohomeClient()
+      ->WaitForServiceToBeAvailable(base::Bind(
+          &ExistingUserController::ContinueLoginWhenCryptohomeAvailable,
+          weak_factory_.GetWeakPtr(), continuation));
 }
 
 void ExistingUserController::DoCompleteLogin(