mojo api for view based lockscreen.

BUG=721524

Review-Url: https://codereview.chromium.org/2876673002
Cr-Commit-Position: refs/heads/master@{#472966}

diff --git a/ash/login/lock_screen_controller.cc b/ash/login/lock_screen_controller.cc
new file mode 100644
index 0000000..5ff835e
--- /dev/null
+++ b/ash/login/lock_screen_controller.cc

@@ -0,0 +1,59 @@
+// 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 "ash/login/lock_screen_controller.h"
+
+#include "chromeos/cryptohome/system_salt_getter.h"
+#include "chromeos/login/auth/user_context.h"
+
+namespace ash {
+
+LockScreenController::LockScreenController() = default;
+
+LockScreenController::~LockScreenController() = default;
+
+void LockScreenController::BindRequest(mojom::LockScreenRequest request) {
+  bindings_.AddBinding(this, std::move(request));
+}
+
+void LockScreenController::AuthenticateUser(const AccountId& account_id,
+                                            const std::string& password,
+                                            bool authenticated_by_pin) {
+  if (!lock_screen_client_)
+    return;
+
+  chromeos::SystemSaltGetter::Get()->GetSystemSalt(base::Bind(
+      &LockScreenController::DoAuthenticateUser, base::Unretained(this),
+      account_id, password, authenticated_by_pin));
+}
+
+void LockScreenController::SetClient(mojom::LockScreenClientPtr client) {
+  lock_screen_client_ = std::move(client);
+}
+
+void LockScreenController::ShowErrorMessage(int32_t login_attempts,
+                                            const std::string& error_text,
+                                            const std::string& help_link_text,
+                                            int32_t help_topic_id) {
+  NOTIMPLEMENTED();
+}
+
+void LockScreenController::ClearErrors() {
+  NOTIMPLEMENTED();
+}
+
+void LockScreenController::DoAuthenticateUser(const AccountId& account_id,
+                                              const std::string& password,
+                                              bool authenticated_by_pin,
+                                              const std::string& system_salt) {
+  // Hash password before sending through mojo.
+  // TODO(xiaoyinh): Pin is hashed differently by using a different salt and
+  // a different hash algorithm. Update this part in PinStorage.
+  chromeos::Key key(password);
+  key.Transform(chromeos::Key::KEY_TYPE_SALTED_SHA256_TOP_HALF, system_salt);
+  lock_screen_client_->AuthenticateUser(account_id, key.GetSecret(),
+                                        authenticated_by_pin);
+}
+
+}  // namespace ash