Remove the last usages of PrefObserver outside of Prefs.

chrome/browser/autofill/autocomplete_history_manager.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/autofill/autocomplete_history_manager.h"
 
 #include <vector>
 
 #include "base/prefs/public/pref_service_base.h"
 #include "base/string16.h"
@@ skipping 98 matching lines @@
 AutocompleteHistoryManager::AutocompleteHistoryManager(
     WebContents* web_contents)
     : content::WebContentsObserver(web_contents),
       pending_query_handle_(0),
       query_id_(0),
       external_delegate_(NULL) {
   browser_context_ = web_contents->GetBrowserContext();
   // May be NULL in unit tests.
   autofill_data_ = AutofillWebDataService::FromBrowserContext(browser_context_);
   autofill_enabled_.Init(prefs::kAutofillEnabled,
-                         PrefServiceBase::FromBrowserContext(browser_context_),
-                         NULL);
+                         PrefServiceBase::FromBrowserContext(browser_context_));
 }
 
 AutocompleteHistoryManager::~AutocompleteHistoryManager() {
   CancelPendingQuery();
 }
 
 bool AutocompleteHistoryManager::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(AutocompleteHistoryManager, message)
@@ skipping 106 matching lines @@
     WebContents* web_contents,
     BrowserContext* browser_context,
     scoped_ptr<AutofillWebDataService> awd)
     : content::WebContentsObserver(web_contents),
       browser_context_(browser_context),
       autofill_data_(awd.Pass()),
       pending_query_handle_(0),
       query_id_(0),
       external_delegate_(NULL) {
   autofill_enabled_.Init(prefs::kAutofillEnabled,
-                         PrefServiceBase::FromBrowserContext(browser_context_),
-                         NULL);
+                         PrefServiceBase::FromBrowserContext(browser_context_));
 }
 
 void AutocompleteHistoryManager::CancelPendingQuery() {
   if (pending_query_handle_) {
     SendSuggestions(NULL);
     if (autofill_data_.get())
       autofill_data_->CancelRequest(pending_query_handle_);
     pending_query_handle_ = 0;
   }
 }
@@ skipping 36 matching lines @@
                                              autofill_icons_,
                                              autofill_unique_ids_));
   }
 
   query_id_ = 0;
   autofill_values_.clear();
   autofill_labels_.clear();
   autofill_icons_.clear();
   autofill_unique_ids_.clear();
 }