Switch TabContentsSyncedTabDelegate to use WebContentsUserData.

chrome/browser/ui/tab_contents/tab_contents.cc

 // Copyright (c) 2012 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/ui/tab_contents/tab_contents.h"
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "chrome/browser/autofill/autocomplete_history_manager.h"
 #include "chrome/browser/autofill/autofill_external_delegate.h"
@@ skipping 136 matching lines @@
       new PasswordManager(contents, password_manager_delegate_.get()));
   PepperBrokerObserver::CreateForWebContents(contents);
   PluginObserver::CreateForWebContents(contents);
   PrefsTabHelper::CreateForWebContents(contents);
   prerender::PrerenderTabHelper::CreateForWebContents(contents);
   safe_browsing::SafeBrowsingTabObserver::CreateForWebContents(contents);
   SearchEngineTabHelper::CreateForWebContents(contents);
   chrome::search::SearchTabHelper::CreateForWebContents(contents);
   SnapshotTabHelper::CreateForWebContents(contents);
   SSLTabHelper::CreateForWebContents(contents);
-  synced_tab_delegate_.reset(new TabContentsSyncedTabDelegate(this));
+  TabContentsSyncedTabDelegate::CreateForWebContents(contents);
   TabSpecificContentSettings::CreateForWebContents(contents);
   TranslateTabHelper::CreateForWebContents(contents);
   ZoomController::CreateForWebContents(contents);
 
 #if defined(ENABLE_AUTOMATION)
   AutomationTabHelper::CreateForWebContents(contents);
 #endif
 
 #if defined(ENABLE_CAPTIVE_PORTAL_DETECTION)
   captive_portal::CaptivePortalTabHelper::CreateForWebContents(contents);
@@ skipping 73 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // WebContentsObserver overrides
 
 void TabContents::WebContentsDestroyed(WebContents* tab) {
   // Destruction of the WebContents should only be done by us from our
   // destructor. Otherwise it's very likely we (or one of the helpers we own)
   // will attempt to access the WebContents and we'll crash.
   DCHECK(in_destructor_);
 }