Keep WKWebView control group users in the control group

ios/chrome/browser/application_context_impl.cc

 // 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.
 
 #include "ios/chrome/browser/application_context_impl.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 76 matching lines @@
 }
 
 // static
 void ApplicationContextImpl::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterStringPref(ios::prefs::kApplicationLocale, std::string());
   registry->RegisterBooleanPref(prefs::kEulaAccepted, false);
   registry->RegisterBooleanPref(metrics::prefs::kMetricsReportingEnabled,
                                 false);
   registry->RegisterBooleanPref(prefs::kLastSessionExitedCleanly, true);
   registry->RegisterBooleanPref(prefs::kMetricsReportingWifiOnly, true);
+  registry->RegisterBooleanPref(prefs::kLastSessionUsedWKWebViewControlGroup,
+                                false);
 }
 
 void ApplicationContextImpl::PreCreateThreads() {
   DCHECK(thread_checker_.CalledOnValidThread());
   ios_chrome_io_thread_.reset(
       new IOSChromeIOThread(GetLocalState(), GetNetLog()));
 }
 
 void ApplicationContextImpl::PreMainMessageLoopRun() {
   DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 249 matching lines @@
           worker_pool->GetSequenceToken(),
           base::SequencedWorkerPool::SKIP_ON_SHUTDOWN));
 
   gcm_driver_ = gcm::CreateGCMDriverDesktop(
       make_scoped_ptr(new gcm::GCMClientFactory), GetLocalState(), store_path,
       GetSystemURLRequestContext(), ::GetChannel(),
       web::WebThread::GetTaskRunnerForThread(web::WebThread::UI),
       web::WebThread::GetTaskRunnerForThread(web::WebThread::IO),
       blocking_task_runner);
 }