[Sync] Refactoring of sync integration test checkers to remove boilerplate await methods.

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

 // Copyright 2016 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_FAKE_SERVER_MATCH_STATUS_CHECKER_H_
 #define CHROME_BROWSER_SYNC_TEST_INTEGRATION_FAKE_SERVER_MATCH_STATUS_CHECKER_H_
 
 #include <string>
 
 #include "chrome/browser/sync/test/integration/status_change_checker.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/test/fake_server/fake_server.h"
 
 namespace fake_server {
 
 // A matcher that checks a generic condition against the fake server. This class
 // is abstract where any subclass will be responsible for implementing some of
 // StatusChangeChecker's virtual methods.
 class FakeServerMatchStatusChecker : public StatusChangeChecker,
                                      public FakeServer::Observer {
  public:
   FakeServerMatchStatusChecker();
-  void Wait();
+  ~FakeServerMatchStatusChecker() override;
+
+  // FakeServer::Observer implementation.
   void OnCommit(const std::string& committer_id,
                 syncer::ModelTypeSet committed_model_types) override;
 
  protected:
   FakeServer* fake_server() const;
 
  private:
   FakeServer* fake_server_;
 };
 
 }  // namespace fake_server
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_FAKE_SERVER_MATCH_STATUS_CHECKER_H_