cros: Remove user directory when encryption migration fails.

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

Index: chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
index 2b69ed620a86f90b23bb89abef5a7770b4f447da..39017def4b8a6f36eb02b04a814d9b3df4f7e2fd 100644
--- a/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/encryption_migration_screen_handler.cc
@@ -16,6 +16,7 @@
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/grit/generated_resources.h"
 #include "chromeos/chromeos_switches.h"
+#include "chromeos/cryptohome/async_method_caller.h"
 #include "chromeos/cryptohome/homedir_methods.h"
 #include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
@@ -312,6 +313,22 @@ void EncryptionMigrationScreenHandler::StopBlockingPowerSave() {
   }
 }
 
+void EncryptionMigrationScreenHandler::RemoveCryptohome() {
+  cryptohome::AsyncMethodCaller::GetInstance()->AsyncRemove(

[fukino, 2017/04/26 11:01:43]

Instead of calling AsyncRemove directly, we should be able to call
UserManager::RemoveUser() to avoid http://crbug.com/715474, but I'm concerned
about that UserManager::RemoveUser() can't remove owner profile.

Maybe we should remove cryptohome by AsyncRemove call and call
UserManager::RemoveUserList() to remove user pod?

[xiyuan, 2017/04/26 17:48:24]

Agree that we should not use RemoveUser().

We can use 
  UserManager::Get()->SaveUserOAuthStatus(
        account_id, user_manager::User::OAUTH2_TOKEN_STATUS_INVALID);

to force user to go through Gaia on the next sign-in. And Gaia flow would
restore the token status on success.

[fukino, 2017/04/27 01:38:23]

Thank you for the suggestion!
Updated the CL to invalidate token status, and confirmed that the user with
missing cryptohome can log in in the first attempt after the call.
Done.

+      cryptohome::Identification(user_context_.GetAccountId()),
+      base::Bind(&EncryptionMigrationScreenHandler::OnRemoveCryptohome,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void EncryptionMigrationScreenHandler::OnRemoveCryptohome(
+    bool success,
+    cryptohome::MountError return_code) {
+  if (!success)
+    LOG(ERROR) << "Removing cryptohome failed. return code: " << return_code;

[xiyuan, 2017/04/26 17:48:24]

nit: LOG_IF(ERROR, !success) << ....

[fukino, 2017/04/27 01:38:23]

Done.

+
+  UpdateUIState(UIState::MIGRATION_FAILED);
+}
+
 cryptohome::KeyDefinition EncryptionMigrationScreenHandler::GetAuthKey() {
   // |auth_key| is created in the same manner as CryptohomeAuthenticator.
   const Key* key = user_context_.GetKey();
@@ -344,12 +361,13 @@ void EncryptionMigrationScreenHandler::OnMigrationProgress(
       DBusThreadManager::Get()->GetPowerManagerClient()->RequestRestart();
       break;
     case cryptohome::DIRCRYPTO_MIGRATION_FAILED:
-      UpdateUIState(UIState::MIGRATION_FAILED);
       // Stop listening to the progress updates.
       DBusThreadManager::Get()
           ->GetCryptohomeClient()
           ->SetDircryptoMigrationProgressHandler(
               CryptohomeClient::DircryptoMigrationProgessHandler());
+      // Shows error screen after removing user directory is completed.
+      RemoveCryptohome();
       break;
     default:
       break;
@@ -357,12 +375,10 @@ void EncryptionMigrationScreenHandler::OnMigrationProgress(
 }
 
 void EncryptionMigrationScreenHandler::OnMigrationRequested(bool success) {
-  // This function is called when MigrateToDircrypto is correctly requested.
-  // It does not mean that the migration is completed. We should know the
-  // completion by DircryptoMigrationProgressHandler. success == false means a
-  // failure in DBus communication.
-  // TODO(fukino): Handle this case. Should we retry or restart?
-  DCHECK(success);
+  if (!success) {
+    LOG(ERROR) << "Requesting MigrateToDircrypto failed. Removing cryptohome.";
+    RemoveCryptohome();

[xiyuan, 2017/04/26 17:48:24]

I think we should only RemoveCryptohome() only when migration really fails. Do
this on failed MigrateToDircrypto call feels too aggressive.

Maybe only do
  UpdateUIState(UIState::MIGRATION_FAILED);

[fukino, 2017/04/27 01:38:23]

Done.

+  }
 }
 
 }  // namespace chromeos