reland of [sync] Add Sessions integration tests

chrome/browser/sync/test/integration/session_hierarchy_match_checker.h

+// Copyright (c) 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 CHROME_BROWSER_SYNC_TEST_INTEGRATION_SESSION_HIERARCHY_MATCH_CHECKER_H_
+#define CHROME_BROWSER_SYNC_TEST_INTEGRATION_SESSION_HIERARCHY_MATCH_CHECKER_H_
+
+#include "chrome/browser/sync/test/integration/single_client_status_change_checker.h"
+#include "components/sync/test/fake_server/fake_server_verifier.h"
+#include "components/sync/test/fake_server/sessions_hierarchy.h"
+
+// Checker to block until the FakeServer records a SessionsHierarchy identical
+// to the SessionsHierarchy specified in the constructor.
+class SessionHierarchyMatchChecker : public SingleClientStatusChangeChecker {
+ public:
+  SessionHierarchyMatchChecker(
+      const fake_server::SessionsHierarchy& sessions_hierarchy,
+      browser_sync::ProfileSyncService* service,
+      fake_server::FakeServer* fake_server);
+
+  // StatusChangeChecker implementation.
+  bool IsExitConditionSatisfied() override;
+  std::string GetDebugMessage() const override;
+
+ private:
+  const fake_server::SessionsHierarchy sessions_hierarchy_;
+  fake_server::FakeServerVerifier verifier_;
+};
+
+#endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_SESSION_HIERARCHY_MATCH_CHECKER_H_