Remove the last usages of PrefObserver outside of Prefs.

chrome/browser/ui/browser.cc

 // Copyright 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 396 matching lines @@
                  BOOKMARK_BAR_STATE_CHANGE_PREF_CHANGE));
   profile_pref_registrar_.Add(
       prefs::kHomePage,
       base::Bind(&Browser::MarkHomePageAsChanged, base::Unretained(this)));
 
   BrowserList::AddBrowser(this);
 
   // NOTE: These prefs all need to be explicitly destroyed in the destructor
   // or you'll get a nasty surprise when you run the incognito tests.
   encoding_auto_detect_.Init(prefs::kWebKitUsesUniversalDetector,
-                             profile_->GetPrefs(), NULL);
+                             profile_->GetPrefs());
 
   if (is_type_tabbed())
     instant_controller_.reset(new chrome::BrowserInstantController(this));
 
 #if 0
   // Disabled for M22. See http://crbug.com/144326.
   device_attached_intent_source_.reset(
       new DeviceAttachedIntentSource(this, (this)));
 #endif
 
@@ skipping 1987 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         content::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }