sync: Re-enable some migration integration tests

chrome/browser/sync/test/integration/status_change_checker.cc

 // Copyright 2013 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 "chrome/browser/sync/test/integration/status_change_checker.h"
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/timer/timer.h"
 
-StatusChangeChecker::StatusChangeChecker()
-  : timed_out_(false),
-    wait_started_(false) {}
+StatusChangeChecker::StatusChangeChecker() : timed_out_(false) {
+}
 
 StatusChangeChecker::~StatusChangeChecker() {}
 
 bool StatusChangeChecker::TimedOut() const {
   return timed_out_;
 }
 
 base::TimeDelta StatusChangeChecker::GetTimeoutDuration() {
   return base::TimeDelta::FromSeconds(45);
 }
 
 void StatusChangeChecker::StartBlockingWait() {
-  DCHECK(!wait_started_) << "This class is intended for one use only.";
-  wait_started_ = true;
-
   base::OneShotTimer<StatusChangeChecker> timer;
   timer.Start(FROM_HERE,
               GetTimeoutDuration(),
               base::Bind(&StatusChangeChecker::OnTimeout,
                          base::Unretained(this)));
 
   {
     base::MessageLoop* loop = base::MessageLoop::current();
     base::MessageLoop::ScopedNestableTaskAllower allow(loop);
     loop->Run();
@@ skipping 10 matching lines @@
     DVLOG(1) << "Await -> Condition met: " << GetDebugMessage();
     StopWaiting();
   }
 }
 
 void StatusChangeChecker::OnTimeout() {
   DVLOG(1) << "Await -> Timed out: " << GetDebugMessage();
   timed_out_ = true;
   StopWaiting();
 }