Switch AlternateErrorPageTabObserver 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 96 matching lines @@
   // Stash this in the WebContents.
   contents->SetUserData(&kTabContentsUserDataKey,
                         new TabContentsUserData(this));
 
   // Create the tab helpers.
 
   // SessionTabHelper comes first because it sets up the tab ID, and other
   // helpers may rely on that.
   SessionTabHelper::CreateForWebContents(contents);
 
+  AlternateErrorPageTabObserver::CreateForWebContents(contents);
   autocomplete_history_manager_.reset(new AutocompleteHistoryManager(contents));
   autofill_delegate_.reset(new TabAutofillManagerDelegate(this));
   autofill_manager_ = new AutofillManager(autofill_delegate_.get(), this);
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kExternalAutofillPopup)) {
     autofill_external_delegate_.reset(
         AutofillExternalDelegate::Create(this, autofill_manager_.get()));
     autofill_manager_->SetExternalDelegate(autofill_external_delegate_.get());
     autocomplete_history_manager_->SetExternalDelegate(
         autofill_external_delegate_.get());
@@ skipping 33 matching lines @@
   synced_tab_delegate_.reset(new TabContentsSyncedTabDelegate(this));
   content_settings_.reset(new TabSpecificContentSettings(contents));
   translate_tab_helper_.reset(new TranslateTabHelper(contents));
   zoom_controller_.reset(new ZoomController(this));
 
 #if !defined(OS_ANDROID)
   web_intent_picker_controller_.reset(new WebIntentPickerController(this));
   sad_tab_helper_.reset(new SadTabHelper(contents));
 #endif
 
-  // Create the per-tab observers.
-  alternate_error_page_tab_observer_.reset(
-      new AlternateErrorPageTabObserver(contents, profile()));
   external_protocol_observer_.reset(new ExternalProtocolObserver(contents));
   navigation_metrics_recorder_.reset(new NavigationMetricsRecorder(contents));
   pdf_tab_observer_.reset(new PDFTabObserver(this));
   pepper_broker_observer_.reset(new PepperBrokerObserver(contents));
   plugin_observer_.reset(new PluginObserver(this));
   safe_browsing_tab_observer_.reset(
       new safe_browsing::SafeBrowsingTabObserver(this));
     webnavigation_observer_.reset(
         new extensions::WebNavigationTabObserver(contents));
 
@@ skipping 68 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_);
 }