cros: Remove user directory when encryption migration fails.

When the migration UI is notified by cryptohome that cryptohome gets unexpected
errors during migration and it gives up migration, we should remove the
user's cryptohome to make sure that the user will be able to log in to
the Desktop next time.

After the user's cryptohome is removed, we get password verification errors
on the existing user pod three times.
It seems an independent issue, so I filed crbug.com/715474 and will look into separately.

BUG=713556
TEST=manually tested by forcing cryptohome fail during migration and confirming the cryptohome is gone.

Review-Url: https://codereview.chromium.org/2838303003
Cr-Commit-Position: refs/heads/master@{#467608}

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

@@ -16,12 +16,14 @@
 #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"
 #include "chromeos/dbus/power_manager/power_supply_properties.pb.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "components/login/localized_values_builder.h"
+#include "components/user_manager/user_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "device/power_save_blocker/power_save_blocker.h"
 #include "ui/base/text/bytes_formatting.h"
@@ -312,6 +314,26 @@ void EncryptionMigrationScreenHandler::StopBlockingPowerSave() {
   }
 }
 
+void EncryptionMigrationScreenHandler::RemoveCryptohome() {
+  // Set invalid token status so that user is forced to go through Gaia on the
+  // next sign-in.
+  user_manager::UserManager::Get()->SaveUserOAuthStatus(
+      user_context_.GetAccountId(),
+      user_manager::User::OAUTH2_TOKEN_STATUS_INVALID);
+  cryptohome::AsyncMethodCaller::GetInstance()->AsyncRemove(
+      cryptohome::Identification(user_context_.GetAccountId()),
+      base::Bind(&EncryptionMigrationScreenHandler::OnRemoveCryptohome,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void EncryptionMigrationScreenHandler::OnRemoveCryptohome(
+    bool success,
+    cryptohome::MountError return_code) {
+  LOG_IF(ERROR, !success) << "Removing cryptohome failed. return code: "
+                          << return_code;
+  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 +366,13 @@ 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 +380,8 @@ 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);
+  LOG_IF(ERROR, !success) << "Requesting MigrateToDircrypto failed.";
+  UpdateUIState(UIState::MIGRATION_FAILED);
 }
 
 }  // namespace chromeos

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

@@ -77,6 +77,9 @@ class EncryptionMigrationScreenHandler : public EncryptionMigrationScreenView,
                             const std::string& mount_hash);
   void StartBlockingPowerSave();
   void StopBlockingPowerSave();
+  // Removes cryptohome and shows the error screen after the removal finishes.
+  void RemoveCryptohome();
+  void OnRemoveCryptohome(bool success, cryptohome::MountError return_code);
 
   // Creates authorization key for MountEx method using |user_context_|.
   cryptohome::KeyDefinition GetAuthKey();