cros: Pull TestLockScreenClient into a separate MockLockScreenClient file.

ash/login/mock_lock_screen_client.h

+// 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.
+
+#ifndef ASH_LOGIN_MOCK_LOCK_SCREEN_CLIENT_H_
+#define ASH_LOGIN_MOCK_LOCK_SCREEN_CLIENT_H_
+
+#include "ash/public/interfaces/lock_screen.mojom.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace ash {
+
+class MockLockScreenClient : public mojom::LockScreenClient {
+ public:
+  MockLockScreenClient();
+  ~MockLockScreenClient() override;
+
+  mojom::LockScreenClientPtr CreateInterfacePtrAndBind();
+
+  // mojom::LockScreenClient:
+  MOCK_METHOD3(AuthenticateUser,
+               void(const AccountId& account_id,
+                    const std::string& password,
+                    bool authenticated_by_pin));
+
+ private:
+  mojo::Binding<ash::mojom::LockScreenClient> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockLockScreenClient);
+};
+
+// Helper method to bind a lock screen client so it receives all mojo calls.
+std::unique_ptr<MockLockScreenClient> BindMockLockScreenClient();
+
+}  // namespace ash
+
+#endif  // ASH_LOGIN_MOCK_LOCK_SCREEN_CLIENT_H_