Add a screen to migrate filesystem encryption from eCryptfs to ext4 crypto.

chrome/browser/chromeos/login/screens/encryption_migration_screen.cc

Index: chrome/browser/chromeos/login/screens/encryption_migration_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/encryption_migration_screen.cc b/chrome/browser/chromeos/login/screens/encryption_migration_screen.cc
new file mode 100644
index 0000000000000000000000000000000000000000..21c9760ae5de647dd7d27c98d6757e3b6dede95b
--- /dev/null
+++ b/chrome/browser/chromeos/login/screens/encryption_migration_screen.cc
@@ -0,0 +1,48 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/login/screens/encryption_migration_screen.h"
+
+#include "base/logging.h"
+#include "chrome/browser/chromeos/login/screens/base_screen_delegate.h"
+#include "chrome/browser/chromeos/login/wizard_controller.h"
+
+namespace chromeos {
+
+EncryptionMigrationScreen::EncryptionMigrationScreen(
+    BaseScreenDelegate* base_screen_delegate,
+    EncryptionMigrationScreenView* view)
+    : BaseScreen(base_screen_delegate, OobeScreen::SCREEN_ENCRYPTION_MIGRATION),
+      view_(view) {
+  DCHECK(view_);
+  if (view_)
+    view_->SetDelegate(this);
+}
+
+EncryptionMigrationScreen::~EncryptionMigrationScreen() {
+  if (view_)
+    view_->SetDelegate(nullptr);
+}
+
+void EncryptionMigrationScreen::Show() {
+  if (view_)
+    view_->Show();
+}
+
+void EncryptionMigrationScreen::Hide() {
+  if (view_)
+    view_->Hide();
+}
+
+void EncryptionMigrationScreen::OnExit() {
+  Finish(ScreenExitCode::ENCRYPTION_MIGRATION_FINISHED);
+}
+
+void EncryptionMigrationScreen::OnViewDestroyed(
+    EncryptionMigrationScreenView* view) {
+  if (view_ == view)
+    view_ = nullptr;
+}
+
+}  // namespace chromeos