Resume encryption migration immediately if the previous migration is incomplete.

chromeos/login/auth/cryptohome_authenticator.cc

Index: chromeos/login/auth/cryptohome_authenticator.cc
diff --git a/chromeos/login/auth/cryptohome_authenticator.cc b/chromeos/login/auth/cryptohome_authenticator.cc
index a301fccce6f4a405e914079f2cd0530f6d77b77c..a4f98d23be13501898b09f071522baf656f68650 100644
--- a/chromeos/login/auth/cryptohome_authenticator.cc
+++ b/chromeos/login/auth/cryptohome_authenticator.cc
@@ -660,10 +660,13 @@ void CryptohomeAuthenticator::OnPasswordChangeDetected() {
     consumer_->OnPasswordChangeDetected();
 }
 
-void CryptohomeAuthenticator::OnOldEncryptionDetected() {
+void CryptohomeAuthenticator::OnOldEncryptionDetected(
+    bool has_incomplete_migration) {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
-  if (consumer_)
-    consumer_->OnOldEncryptionDetected(current_state_->user_context);
+  if (consumer_) {
+    consumer_->OnOldEncryptionDetected(current_state_->user_context,
+                                       has_incomplete_migration);
+  }
 }
 
 void CryptohomeAuthenticator::OnAuthFailure(const AuthFailure& error) {
@@ -865,12 +868,14 @@ void CryptohomeAuthenticator::Resolve() {
       break;
     }
     case FAILED_OLD_ENCRYPTION:
+    case FAILED_PREVIOUS_MIGRATION_INCOMPLETE:
       // In this case, we tried to create/mount cryptohome and failed
       // because the file system is encrypted in old format.
       // Chrome will show a screen which asks user to migrate the encryption.
       task_runner_->PostTask(
           FROM_HERE,
-          base::Bind(&CryptohomeAuthenticator::OnOldEncryptionDetected, this));
+          base::Bind(&CryptohomeAuthenticator::OnOldEncryptionDetected, this,
+                     state == FAILED_PREVIOUS_MIGRATION_INCOMPLETE));
       break;
     default:
       NOTREACHED();
@@ -948,6 +953,10 @@ CryptohomeAuthenticator::ResolveCryptohomeFailureState() {
       cryptohome::MOUNT_ERROR_OLD_ENCRYPTION) {
     return FAILED_OLD_ENCRYPTION;
   }
+  if (current_state_->cryptohome_code() ==
+      cryptohome::MOUNT_ERROR_PREVIOUS_MIGRATION_INCOMPLETE) {
+    return FAILED_PREVIOUS_MIGRATION_INCOMPLETE;
+  }
 
   // Return intermediate states in the following case:
   // when there is an online result to use;