DevTools: Fix a DCHECK failure during browser shutdown.

chrome/browser/devtools/device/port_forwarding_controller.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 "chrome/browser/devtools/device/port_forwarding_controller.h"
 
 #include <algorithm>
 #include <map>
 
 #include "base/bind.h"
@@ skipping 517 matching lines @@
       pref_service_(profile->GetPrefs()),
       listening_(false) {
   pref_change_registrar_.Init(pref_service_);
   base::Closure callback = base::Bind(
       &PortForwardingController::OnPrefsChange, base::Unretained(this));
   pref_change_registrar_.Add(prefs::kDevToolsPortForwardingEnabled, callback);
   pref_change_registrar_.Add(prefs::kDevToolsPortForwardingConfig, callback);
   OnPrefsChange();
 }
 
-PortForwardingController::~PortForwardingController() {
+
+PortForwardingController::~PortForwardingController() {}
+
+void PortForwardingController::Shutdown() {
   // Existing connection will not be shut down. This might be confusing for
   // some users, but the opposite is more confusing.
   StopListening();
 }
 
 void PortForwardingController::AddListener(Listener* listener) {
   listeners_.push_back(listener);
 }
 
 void PortForwardingController::RemoveListener(Listener* listener) {
@@ skipping 110 matching lines @@
           "PortForwardingController",
           BrowserContextDependencyManager::GetInstance()) {}
 
 PortForwardingController::Factory::~Factory() {}
 
 KeyedService* PortForwardingController::Factory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   Profile* profile = Profile::FromBrowserContext(context);
   return new PortForwardingController(profile);
 }