Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/captive_portal/captive_portal_service.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/captive_portal/captive_portal_service.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 253 matching lines @@
     // "failures", to trigger backoff.
     backoff_entry_->SetCustomReleaseTime(now + retry_after_delta);
     backoff_entry_->InformOfRequest(false);
   }
 
   last_check_time_ = now;
 
   OnResult(result);
 }
 
-void CaptivePortalService::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
+void CaptivePortalService::OnPreferenceChanged(PrefServiceBase* service,
+                                               const std::string& pref_name) {
   DCHECK(CalledOnValidThread());
-  DCHECK_EQ(chrome::NOTIFICATION_PREF_CHANGED, type);
-  DCHECK_EQ(std::string(prefs::kAlternateErrorPagesEnabled),
-            *content::Details<std::string>(details).ptr());
+  DCHECK_EQ(std::string(prefs::kAlternateErrorPagesEnabled), pref_name);
   UpdateEnabledState();
 }
 
 void CaptivePortalService::Shutdown() {
   DCHECK(CalledOnValidThread());
   if (enabled_) {
     RecordRepeatHistograms(
         last_detection_result_,
         num_checks_with_same_result_,
         GetCurrentTimeTicks() - first_check_time_with_same_result_);
@@ skipping 71 matching lines @@
 
 bool CaptivePortalService::DetectionInProgress() const {
   return state_ == STATE_CHECKING_FOR_PORTAL;
 }
 
 bool CaptivePortalService::TimerRunning() const {
   return check_captive_portal_timer_.IsRunning();
 }
 
 }  // namespace captive_portal