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

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

 // Copyright 2014 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_MULTI_CLIENT_STATUS_CHANGE_CHECKER_H_
 #define CHROME_BROWSER_SYNC_TEST_INTEGRATION_MULTI_CLIENT_STATUS_CHANGE_CHECKER_H_
 
+#include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
+#include "base/scoped_observer.h"
 #include "base/time/time.h"
 #include "chrome/browser/sync/test/integration/status_change_checker.h"
 #include "components/sync/driver/sync_service_observer.h"
 
 namespace browser_sync {
 class ProfileSyncService;
 }  // namespace browser_sync
 
 // This class provides some common functionality for StatusChangeCheckers that
 // observe many ProfileSyncServices.  This class is abstract.  Its descendants
 // are expected to provide additional functionality.
 class MultiClientStatusChangeChecker : public StatusChangeChecker,
                                        public sync_driver::SyncServiceObserver {
  public:
   explicit MultiClientStatusChangeChecker(
       std::vector<browser_sync::ProfileSyncService*> services);
   ~MultiClientStatusChangeChecker() override;
 
   // Called when waiting times out.
   void OnTimeout();
 
-  // Blocks until the exit condition is satisfied or a timeout occurs.
-  void Wait();
-
   // sync_driver::SyncServiceObserver implementation.
   void OnStateChanged() override;
 
   // StatusChangeChecker implementations and stubs.
   bool IsExitConditionSatisfied() override = 0;
   std::string GetDebugMessage() const override = 0;
 
  protected:
   const std::vector<browser_sync::ProfileSyncService*>& services() {
     return services_;
   }
 
  private:
   std::vector<browser_sync::ProfileSyncService*> services_;
+  ScopedObserver<browser_sync::ProfileSyncService,
+                 MultiClientStatusChangeChecker>
+      scoped_observer_;
 };
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_MULTI_CLIENT_STATUS_CHANGE_CHECKER_H_