Wait for Cryptohome service to be available on login.

chrome/browser/chromeos/login/existing_user_controller.h

Index: chrome/browser/chromeos/login/existing_user_controller.h
diff --git a/chrome/browser/chromeos/login/existing_user_controller.h b/chrome/browser/chromeos/login/existing_user_controller.h
index 32f8a497364c3e69c7bb2354b48da675ea897c42..f3a2ee72898555f2e15ee5769bdaf8f989da7436 100644
--- a/chrome/browser/chromeos/login/existing_user_controller.h
+++ b/chrome/browser/chromeos/login/existing_user_controller.h
@@ -251,6 +251,10 @@ class ExistingUserController
   // auto-login timer is started.
   void PerformLoginFinishedActions(bool start_auto_login_timer);
 
+  // Invokes |continuation| after verifying that cryptohome service is available
+  void ContinueLoginWhenCryptohomeAvailable(const base::Closure& continuation,

[Roman Sorokin (ftl), 2017/04/18 13:30:42]

Why not OnceClosure?

[Sergey Poromov, 2017/04/18 14:16:39]

Because it's a callback from ContinueLoginIfDeviceNotDisabled and it can't be
single-owned since it's sometimes is passed as part of a callback into
cros_settings_->PrepareTrustedValues()

[Roman Sorokin (ftl), 2017/04/18 14:30:18]

I guess passing it to PrepareTrustedValues is not a problem. But yeah, this
should not be part of this CL. 

[Sergey Poromov, 2017/04/18 14:30:19]

But on the other hand it could be left as (Repeated)Closure in
ContinueLoginIfDeviceNotDisabled, but converted to OnceClosure as soon as passed
to ContinueLoginWhenCryptohomeAvailable - thanks!
Done.

+                                            bool service_is_available);
+
   // Invokes |continuation| after verifying that the device is not disabled.
   void ContinueLoginIfDeviceNotDisabled(const base::Closure& continuation);