Use PrefChangeRegistrar everywhere

BUG=54955
TEST=PrefChangeRegistrarTest.*

Review URL: http://codereview.chromium.org/3304015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60169 0039d316-1c4b-4281-b951-d872f2087c98

47 files changed, 254 insertions, 210 deletions

diff --git a/chrome/browser/background_mode_manager.cc b/chrome/browser/background_mode_manager.cc
index d675958..0882e4b 100644
--- a/chrome/browser/background_mode_manager.cc
+++ b/chrome/browser/background_mode_manager.cc
@@ -148,7 +148,8 @@ BackgroundModeManager::BackgroundModeManager(Profile* profile,
                  NotificationService::AllSources());
 
   // Listen for changes to the background mode preference.
-  profile_->GetPrefs()->AddPrefObserver(prefs::kBackgroundModeEnabled, this);
+  pref_registrar_.Init(profile_->GetPrefs());
+  pref_registrar_.Add(prefs::kBackgroundModeEnabled, this);
 }
 
 BackgroundModeManager::~BackgroundModeManager() {
@@ -157,10 +158,6 @@ BackgroundModeManager::~BackgroundModeManager() {
   // because in an actual running system we'd get an APP_TERMINATING
   // notification before being destroyed.
   EndBackgroundMode();
-  // Manually remove our pref observer so we don't get notified for prefs
-  // changes (have to do it manually because we can't use the registrar for
-  // prefs notifications).
-  profile_->GetPrefs()->RemovePrefObserver(prefs::kBackgroundModeEnabled, this);
 }
 
 bool BackgroundModeManager::IsBackgroundModeEnabled() {
diff --git a/chrome/browser/background_mode_manager.h b/chrome/browser/background_mode_manager.h
index 46e8847..52f37da 100644
--- a/chrome/browser/background_mode_manager.h
+++ b/chrome/browser/background_mode_manager.h
@@ -8,6 +8,7 @@
 
 #include "app/menus/simple_menu_model.h"
 #include "base/gtest_prod_util.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/status_icons/status_icon.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
@@ -142,6 +143,9 @@ class BackgroundModeManager
   // Reference to our status icon (if any) - owned by the StatusTray.
   StatusIcon* status_icon_;
 
+  // Ensure observed preferences are properly cleaned up.
+  PrefChangeRegistrar pref_registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(BackgroundModeManager);
 };
 
diff --git a/chrome/browser/cocoa/content_settings_dialog_controller.h b/chrome/browser/cocoa/content_settings_dialog_controller.h
index d48b962..8fe92da 100644
--- a/chrome/browser/cocoa/content_settings_dialog_controller.h
+++ b/chrome/browser/cocoa/content_settings_dialog_controller.h
@@ -7,6 +7,7 @@
 #import "base/cocoa_protocols_mac.h"
 #include "base/scoped_ptr.h"
 #include "chrome/common/content_settings_types.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_member.h"
 
 // Index of the "enabled" and "disabled" radio group settings in all tabs except
@@ -50,6 +51,7 @@ class Profile;
   Profile* profile_;  // weak
   IntegerPrefMember lastSelectedTab_;
   BooleanPrefMember clearSiteDataOnExit_;
+  PrefChangeRegistrar registrar_;
   scoped_ptr<ContentSettingsDialogControllerInternal::PrefObserverBridge>
       observer_;  // Watches for pref changes.
 }
diff --git a/chrome/browser/cocoa/content_settings_dialog_controller.mm b/chrome/browser/cocoa/content_settings_dialog_controller.mm
index 0c71fd9..70287cc 100644
--- a/chrome/browser/cocoa/content_settings_dialog_controller.mm
+++ b/chrome/browser/cocoa/content_settings_dialog_controller.mm
@@ -140,11 +140,11 @@ class PrefObserverDisabler {
     // Manually observe notifications for preferences that are grouped in
     // the HostContentSettingsMap or GeolocationContentSettingsMap.
     PrefService* prefs = profile_->GetPrefs();
-    prefs->AddPrefObserver(prefs::kBlockThirdPartyCookies, observer_.get());
-    prefs->AddPrefObserver(prefs::kBlockNonsandboxedPlugins, observer_.get());
-    prefs->AddPrefObserver(prefs::kDefaultContentSettings, observer_.get());
-    prefs->AddPrefObserver(prefs::kGeolocationDefaultContentSetting,
-                           observer_.get());
+    registrar_.Init(prefs);
+    registrar_.Add(prefs::kBlockThirdPartyCookies, observer_.get());
+    registrar_.Add(prefs::kBlockNonsandboxedPlugins, observer_.get());
+    registrar_.Add(prefs::kDefaultContentSettings, observer_.get());
+    registrar_.Add(prefs::kGeolocationDefaultContentSetting, observer_.get());
 
     // We don't need to observe changes in this value.
     lastSelectedTab_.Init(prefs::kContentSettingsWindowLastTabIndex,
@@ -153,20 +153,6 @@ class PrefObserverDisabler {
   return self;
 }
 
-- (void)dealloc {
-  if (profile_) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->RemovePrefObserver(prefs::kBlockThirdPartyCookies, observer_.get());
-    prefs->RemovePrefObserver(prefs::kBlockNonsandboxedPlugins,
-                              observer_.get());
-    prefs->RemovePrefObserver(prefs::kDefaultContentSettings, observer_.get());
-    prefs->RemovePrefObserver(prefs::kGeolocationDefaultContentSetting,
-                              observer_.get());
-  }
-
-  [super dealloc];
-}
-
 - (void)closeExceptionsSheet {
   NSWindow* attachedSheet = [[self window] attachedSheet];
   if (attachedSheet) {
diff --git a/chrome/browser/cocoa/extensions/extension_action_context_menu.mm b/chrome/browser/cocoa/extensions/extension_action_context_menu.mm
index 10ea079..81aa61e 100644
--- a/chrome/browser/cocoa/extensions/extension_action_context_menu.mm
+++ b/chrome/browser/cocoa/extensions/extension_action_context_menu.mm
@@ -18,6 +18,7 @@
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/extensions/extension_tabs_module.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profile.h"
 #include "chrome/common/extensions/extension.h"
@@ -71,14 +72,10 @@ class DevmodeObserver : public NotificationObserver {
   DevmodeObserver(ExtensionActionContextMenu* menu,
                              PrefService* service)
       : menu_(menu), pref_service_(service) {
-    pref_service_->AddPrefObserver(prefs::kExtensionsUIDeveloperMode,
-                                   this);
-  }
-
-  ~DevmodeObserver() {
-    pref_service_->RemovePrefObserver(prefs::kExtensionsUIDeveloperMode,
-                                      this);
+    registrar_.Init(pref_service_);
+    registrar_.Add(prefs::kExtensionsUIDeveloperMode, this);
   }
+  virtual ~DevmodeObserver() {}
 
   void Observe(NotificationType type,
                const NotificationSource& source,
@@ -92,6 +89,7 @@ class DevmodeObserver : public NotificationObserver {
  private:
   ExtensionActionContextMenu* menu_;
   PrefService* pref_service_;
+  PrefChangeRegistrar registrar_;
 };
 
 }  // namespace extension_action_context_menu
diff --git a/chrome/browser/cocoa/preferences_window_controller.h b/chrome/browser/cocoa/preferences_window_controller.h
index e7b8383..54d4778 100644
--- a/chrome/browser/cocoa/preferences_window_controller.h
+++ b/chrome/browser/cocoa/preferences_window_controller.h
@@ -9,6 +9,7 @@
 #include "chrome/browser/options_window.h"
 #include "chrome/browser/prefs/pref_member.h"
 #include "chrome/browser/prefs/pref_set_observer.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 
 namespace PreferencesWindowControllerInternal {
 class PrefObserverBridge;
@@ -45,6 +46,7 @@ class ProfileSyncService;
   ProfileSyncService* syncService_;
   scoped_ptr<PreferencesWindowControllerInternal::PrefObserverBridge>
       observer_;  // Watches for pref changes.
+  PrefChangeRegistrar registrar_;  // Manages pref change observer registration.
   scoped_nsobject<WindowSizeAutosaver> sizeSaver_;
   NSView* currentPrefsView_;  // weak ref - current prefs page view.
   scoped_ptr<PreferencesWindowControllerInternal::ManagedPrefsBannerState>
diff --git a/chrome/browser/cocoa/preferences_window_controller.mm b/chrome/browser/cocoa/preferences_window_controller.mm
index c7c2b7b..0f11f63 100644
--- a/chrome/browser/cocoa/preferences_window_controller.mm
+++ b/chrome/browser/cocoa/preferences_window_controller.mm
@@ -330,7 +330,6 @@ CGFloat AutoSizeUnderTheHoodContent(NSView* view,
 // Record the user performed a certain action and save the preferences.
 - (void)recordUserAction:(const UserMetricsAction&) action;
 - (void)registerPrefObservers;
-- (void)unregisterPrefObservers;
 
 // KVC setter methods.
 - (void)setNewTabPageIsHomePageIndex:(NSInteger)val;
@@ -761,7 +760,6 @@ class ManagedPrefsBannerState : public policy::ManagedPrefsBannerBase {
     syncService_->RemoveObserver(observer_.get());
   }
   [[NSNotificationCenter defaultCenter] removeObserver:self];
-  [self unregisterPrefObservers];
   [animation_ setDelegate:nil];
   [animation_ stopAnimation];
   [super dealloc];
@@ -781,7 +779,8 @@ class ManagedPrefsBannerState : public policy::ManagedPrefsBannerBase {
   if (!prefs_) return;
 
   // Basics panel
-  prefs_->AddPrefObserver(prefs::kURLsToRestoreOnStartup, observer_.get());
+  registrar_.Init(prefs_);
+  registrar_.Add(prefs::kURLsToRestoreOnStartup, observer_.get());
   restoreOnStartup_.Init(prefs::kRestoreOnStartup, prefs_, observer_.get());
   newTabPageIsHomePage_.Init(prefs::kHomePageIsNewTabPage,
                              prefs_, observer_.get());
@@ -823,17 +822,6 @@ class ManagedPrefsBannerState : public policy::ManagedPrefsBannerBase {
   lastSelectedPage_.Init(prefs::kOptionsWindowLastTabIndex, local, NULL);
 }
 
-// Clean up what was registered in -registerPrefObservers. We only have to
-// clean up the non-PrefMember registrations.
-- (void)unregisterPrefObservers {
-  if (!prefs_) return;
-
-  // Basics
-  prefs_->RemovePrefObserver(prefs::kURLsToRestoreOnStartup, observer_.get());
-
-  // Nothing to do for other panels...
-}
-
 // Called when the window wants to be closed.
 - (BOOL)windowShouldClose:(id)sender {
   // Stop any animation and clear the delegate to avoid stale pointers.
diff --git a/chrome/browser/dom_ui/core_options_handler.cc b/chrome/browser/dom_ui/core_options_handler.cc
index 2739ebc..849e768b 100644
--- a/chrome/browser/dom_ui/core_options_handler.cc
+++ b/chrome/browser/dom_ui/core_options_handler.cc
@@ -88,6 +88,13 @@ void CoreOptionsHandler::Uninitialize() {
   }
 }
 
+DOMMessageHandler* CoreOptionsHandler::Attach(DOMUI* dom_ui) {
+  DOMMessageHandler* result = DOMMessageHandler::Attach(dom_ui);
+  DCHECK(dom_ui_);
+  registrar_.Init(dom_ui_->GetProfile()->GetPrefs());
+  return result;
+}
+
 void CoreOptionsHandler::Observe(NotificationType type,
                                  const NotificationSource& source,
                                  const NotificationDetails& details) {
@@ -138,9 +145,7 @@ Value* CoreOptionsHandler::FetchPref(const std::string& pref_name) {
 }
 
 void CoreOptionsHandler::ObservePref(const std::string& pref_name) {
-  DCHECK(dom_ui_);
-  PrefService* pref_service = dom_ui_->GetProfile()->GetPrefs();
-  pref_service->AddPrefObserver(pref_name.c_str(), this);
+  registrar_.Add(pref_name.c_str(), this);
 }
 
 void CoreOptionsHandler::SetPref(const std::string& pref_name,
@@ -185,9 +190,7 @@ void CoreOptionsHandler::ProcessUserMetric(Value::ValueType pref_type,
 }
 
 void CoreOptionsHandler::StopObservingPref(const std::string& path) {
-  DCHECK(dom_ui_);
-  PrefService* pref_service = dom_ui_->GetProfile()->GetPrefs();
-  pref_service->RemovePrefObserver(path.c_str(), this);
+  registrar_.Remove(path.c_str(), this);
 }
 
 void CoreOptionsHandler::HandleFetchPrefs(const ListValue* args) {
diff --git a/chrome/browser/dom_ui/core_options_handler.h b/chrome/browser/dom_ui/core_options_handler.h
index 748ab83..fd94d10 100644
--- a/chrome/browser/dom_ui/core_options_handler.h
+++ b/chrome/browser/dom_ui/core_options_handler.h
@@ -11,6 +11,7 @@
 
 #include "base/values.h"
 #include "chrome/browser/dom_ui/options_ui.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 
 // Core options UI handler.
 // Handles resource and JS calls common to all options sub-pages.
@@ -22,7 +23,6 @@ class CoreOptionsHandler : public OptionsPageUIHandler {
   virtual void GetLocalizedValues(DictionaryValue* localized_strings);
   virtual void Uninitialize();
 
-
   // NotificationObserver implementation.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
@@ -30,6 +30,7 @@ class CoreOptionsHandler : public OptionsPageUIHandler {
 
   // DOMMessageHandler implementation.
   virtual void RegisterMessages();
+  virtual DOMMessageHandler* Attach(DOMUI* dom_ui);
 
  protected:
   // Fetches a pref value of given |pref_name|.
@@ -87,6 +88,8 @@ class CoreOptionsHandler : public OptionsPageUIHandler {
 
   void NotifyPrefChanged(const std::string* pref_name);
 
+  PrefChangeRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(CoreOptionsHandler);
 };
 
diff --git a/chrome/browser/dom_ui/ntp_resource_cache.cc b/chrome/browser/dom_ui/ntp_resource_cache.cc
index 169aea0..50964c9 100644
--- a/chrome/browser/dom_ui/ntp_resource_cache.cc
+++ b/chrome/browser/dom_ui/ntp_resource_cache.cc
@@ -130,15 +130,9 @@ NTPResourceCache::NTPResourceCache(Profile* profile) : profile_(profile) {
                  NotificationService::AllSources());
 
   // Watch for pref changes that cause us to need to invalidate the HTML cache.
-  PrefService* pref_service = profile_->GetPrefs();
-  pref_service->AddPrefObserver(prefs::kShowBookmarkBar, this);
-  pref_service->AddPrefObserver(prefs::kNTPShownSections, this);
-}
-
-NTPResourceCache::~NTPResourceCache() {
-  PrefService* pref_service = profile_->GetPrefs();
-  pref_service->RemovePrefObserver(prefs::kShowBookmarkBar, this);
-  pref_service->RemovePrefObserver(prefs::kNTPShownSections, this);
+  pref_change_registrar_.Init(profile_->GetPrefs());
+  pref_change_registrar_.Add(prefs::kShowBookmarkBar, this);
+  pref_change_registrar_.Add(prefs::kNTPShownSections, this);
 }
 
 RefCountedBytes* NTPResourceCache::GetNewTabHTML(bool is_off_the_record) {
diff --git a/chrome/browser/dom_ui/ntp_resource_cache.h b/chrome/browser/dom_ui/ntp_resource_cache.h
index f669325..3cdc3e5 100644
--- a/chrome/browser/dom_ui/ntp_resource_cache.h
+++ b/chrome/browser/dom_ui/ntp_resource_cache.h
@@ -10,6 +10,7 @@
 #include "base/ref_counted.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 
 class Profile;
 class RefCountedBytes;
@@ -19,7 +20,7 @@ class RefCountedBytes;
 class NTPResourceCache : public NotificationObserver {
  public:
   explicit NTPResourceCache(Profile* profile);
-  virtual ~NTPResourceCache();
+  virtual ~NTPResourceCache() {}
 
   RefCountedBytes* GetNewTabHTML(bool is_off_the_record);
   RefCountedBytes* GetNewTabCSS(bool is_off_the_record);
@@ -43,6 +44,7 @@ class NTPResourceCache : public NotificationObserver {
   scoped_refptr<RefCountedBytes> new_tab_css_;
 
   NotificationRegistrar registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPResourceCache);
 };
diff --git a/chrome/browser/dom_ui/shown_sections_handler.cc b/chrome/browser/dom_ui/shown_sections_handler.cc
index 4af2d0b..94a49a4 100644
--- a/chrome/browser/dom_ui/shown_sections_handler.cc
+++ b/chrome/browser/dom_ui/shown_sections_handler.cc
@@ -50,11 +50,8 @@ int ShownSectionsHandler::GetShownSections(PrefService* prefs) {
 
 ShownSectionsHandler::ShownSectionsHandler(PrefService* pref_service)
     : pref_service_(pref_service) {
-  pref_service_->AddPrefObserver(prefs::kNTPShownSections, this);
-}
-
-ShownSectionsHandler::~ShownSectionsHandler() {
-  pref_service_->RemovePrefObserver(prefs::kNTPShownSections, this);
+  registrar_.Init(pref_service);
+  registrar_.Add(prefs::kNTPShownSections, this);
 }
 
 void ShownSectionsHandler::RegisterMessages() {
diff --git a/chrome/browser/dom_ui/shown_sections_handler.h b/chrome/browser/dom_ui/shown_sections_handler.h
index 8821d640..39428bb 100644
--- a/chrome/browser/dom_ui/shown_sections_handler.h
+++ b/chrome/browser/dom_ui/shown_sections_handler.h
@@ -8,6 +8,7 @@
 
 #include "chrome/browser/dom_ui/dom_ui.h"
 #include "chrome/common/notification_observer.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 
 class DOMUI;
 class Value;
@@ -28,7 +29,7 @@ class ShownSectionsHandler : public DOMMessageHandler,
                              public NotificationObserver {
  public:
   explicit ShownSectionsHandler(PrefService* pref_service);
-  virtual ~ShownSectionsHandler();
+  virtual ~ShownSectionsHandler() {}
 
   // Helper to get the current shown sections.
   static int GetShownSections(PrefService* pref_service);
@@ -55,6 +56,7 @@ class ShownSectionsHandler : public DOMMessageHandler,
 
  private:
   PrefService* pref_service_;
+  PrefChangeRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(ShownSectionsHandler);
 };
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index 79810c0..512772d 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -548,8 +548,9 @@ ExtensionsService::ExtensionsService(Profile* profile,
                  NotificationService::AllSources());
   registrar_.Add(this, NotificationType::EXTENSION_PROCESS_TERMINATED,
                  NotificationService::AllSources());
-  prefs->AddPrefObserver(prefs::kExtensionInstallAllowList, this);
-  prefs->AddPrefObserver(prefs::kExtensionInstallDenyList, this);
+  pref_change_registrar_.Init(prefs);
+  pref_change_registrar_.Add(prefs::kExtensionInstallAllowList, this);
+  pref_change_registrar_.Add(prefs::kExtensionInstallDenyList, this);
 
   // Set up the ExtensionUpdater
   if (autoupdate_enabled) {
@@ -1188,11 +1189,7 @@ void ExtensionsService::UpdateExtensionBlacklist(
 }
 
 void ExtensionsService::DestroyingProfile() {
-  profile_->GetPrefs()->RemovePrefObserver(
-      prefs::kExtensionInstallAllowList, this);
-  profile_->GetPrefs()->RemovePrefObserver(
-      prefs::kExtensionInstallDenyList, this);
-
+  pref_change_registrar_.RemoveAll();
   profile_ = NULL;
 }
 
diff --git a/chrome/browser/extensions/extensions_service.h b/chrome/browser/extensions/extensions_service.h
index 211bc8de..1c50434 100644
--- a/chrome/browser/extensions/extensions_service.h
+++ b/chrome/browser/extensions/extensions_service.h
@@ -28,6 +28,7 @@
 #include "chrome/browser/extensions/extensions_quota_service.h"
 #include "chrome/browser/extensions/external_extension_provider.h"
 #include "chrome/browser/extensions/sandboxed_extension_unpacker.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
 #include "chrome/common/extensions/extension.h"
@@ -484,6 +485,7 @@ class ExtensionsService
   OrphanedDevTools orphaned_dev_tools_;
 
   NotificationRegistrar registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   // Keeps track of menu items added by extensions.
   ExtensionMenuManager menu_manager_;
diff --git a/chrome/browser/extensions/extensions_service_unittest.cc b/chrome/browser/extensions/extensions_service_unittest.cc
index 281e9cb..60a6910 100644
--- a/chrome/browser/extensions/extensions_service_unittest.cc
+++ b/chrome/browser/extensions/extensions_service_unittest.cc
@@ -2476,8 +2476,7 @@ TEST(ExtensionsServiceTestSimple, Enabledness) {
 
   // By default, we are enabled.
   command_line.reset(new CommandLine(CommandLine::ARGUMENTS_ONLY));
-  service = new ExtensionsService(profile.get(), command_line.get(),
-      profile->GetPrefs(), install_dir, false);
+  service = profile->CreateExtensionsService(command_line.get(), install_dir);
   EXPECT_TRUE(service->extensions_enabled());
   service->Init();
   loop.RunAllPending();
@@ -2487,8 +2486,7 @@ TEST(ExtensionsServiceTestSimple, Enabledness) {
   recorder.set_ready(false);
   profile.reset(new TestingProfile());
   command_line->AppendSwitch(switches::kDisableExtensions);
-  service = new ExtensionsService(profile.get(), command_line.get(),
-      profile->GetPrefs(), install_dir, false);
+  service = profile->CreateExtensionsService(command_line.get(), install_dir);
   EXPECT_FALSE(service->extensions_enabled());
   service->Init();
   loop.RunAllPending();
@@ -2497,8 +2495,7 @@ TEST(ExtensionsServiceTestSimple, Enabledness) {
   recorder.set_ready(false);
   profile.reset(new TestingProfile());
   profile->GetPrefs()->SetBoolean(prefs::kDisableExtensions, true);
-  service = new ExtensionsService(profile.get(), command_line.get(),
-      profile->GetPrefs(), install_dir, false);
+  service = profile->CreateExtensionsService(command_line.get(), install_dir);
   EXPECT_FALSE(service->extensions_enabled());
   service->Init();
   loop.RunAllPending();
@@ -2508,8 +2505,7 @@ TEST(ExtensionsServiceTestSimple, Enabledness) {
   profile.reset(new TestingProfile());
   profile->GetPrefs()->SetBoolean(prefs::kDisableExtensions, true);
   command_line.reset(new CommandLine(CommandLine::ARGUMENTS_ONLY));
-  service = new ExtensionsService(profile.get(), command_line.get(),
-      profile->GetPrefs(), install_dir, false);
+  service = profile->CreateExtensionsService(command_line.get(), install_dir);
   EXPECT_FALSE(service->extensions_enabled());
   service->Init();
   loop.RunAllPending();
diff --git a/chrome/browser/gtk/gtk_theme_provider.cc b/chrome/browser/gtk/gtk_theme_provider.cc
index 7e5a2c2..5bcd8a3 100644
--- a/chrome/browser/gtk/gtk_theme_provider.cc
+++ b/chrome/browser/gtk/gtk_theme_provider.cc
@@ -258,7 +258,6 @@ GtkThemeProvider::GtkThemeProvider()
 }
 
 GtkThemeProvider::~GtkThemeProvider() {
-  profile()->GetPrefs()->RemovePrefObserver(prefs::kUsesSystemTheme, this);
   gtk_widget_destroy(fake_window_);
   gtk_widget_destroy(fake_frame_);
   fake_label_.Destroy();
@@ -273,7 +272,8 @@ GtkThemeProvider::~GtkThemeProvider() {
 }
 
 void GtkThemeProvider::Init(Profile* profile) {
-  profile->GetPrefs()->AddPrefObserver(prefs::kUsesSystemTheme, this);
+  registrar_.Init(profile->GetPrefs());
+  registrar_.Add(prefs::kUsesSystemTheme, this);
   use_gtk_ = profile->GetPrefs()->GetBoolean(prefs::kUsesSystemTheme);
 
   BrowserThemeProvider::Init(profile);
diff --git a/chrome/browser/gtk/gtk_theme_provider.h b/chrome/browser/gtk/gtk_theme_provider.h
index 33b1ec2..2ecef7a 100644
--- a/chrome/browser/gtk/gtk_theme_provider.h
+++ b/chrome/browser/gtk/gtk_theme_provider.h
@@ -12,6 +12,7 @@
 #include "app/gtk_integers.h"
 #include "app/gtk_signal.h"
 #include "base/scoped_ptr.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/gtk/owned_widget_gtk.h"
 #include "chrome/browser/themes/browser_theme_provider.h"
 #include "chrome/common/notification_observer.h"
@@ -275,6 +276,8 @@ class GtkThemeProvider : public BrowserThemeProvider,
   PerDisplaySurfaceMap per_display_surfaces_;
   PerDisplaySurfaceMap per_display_unthemed_surfaces_;
 
+  PrefChangeRegistrar registrar_;
+
   // This is a dummy widget that only exists so we have something to pass to
   // gtk_widget_render_icon().
   static GtkWidget* icon_widget_;
diff --git a/chrome/browser/gtk/options/general_page_gtk.cc b/chrome/browser/gtk/options/general_page_gtk.cc
index fb4db2b..734ee8c 100644
--- a/chrome/browser/gtk/options/general_page_gtk.cc
+++ b/chrome/browser/gtk/options/general_page_gtk.cc
@@ -95,8 +95,9 @@ GeneralPageGtk::GeneralPageGtk(Profile* profile)
       InitDefaultBrowserGroup(), false);
 #endif
 
-  profile->GetPrefs()->AddPrefObserver(prefs::kRestoreOnStartup, this);
-  profile->GetPrefs()->AddPrefObserver(prefs::kURLsToRestoreOnStartup, this);
+  registrar_.Init(profile->GetPrefs());
+  registrar_.Add(prefs::kRestoreOnStartup, this);
+  registrar_.Add(prefs::kURLsToRestoreOnStartup, this);
 
   new_tab_page_is_home_page_.Init(prefs::kHomePageIsNewTabPage,
       profile->GetPrefs(), this);
@@ -108,10 +109,6 @@ GeneralPageGtk::GeneralPageGtk(Profile* profile)
 }
 
 GeneralPageGtk::~GeneralPageGtk() {
-  profile()->GetPrefs()->RemovePrefObserver(prefs::kRestoreOnStartup, this);
-  profile()->GetPrefs()->RemovePrefObserver(
-      prefs::kURLsToRestoreOnStartup, this);
-
   if (template_url_model_)
     template_url_model_->RemoveObserver(this);
 
diff --git a/chrome/browser/gtk/options/general_page_gtk.h b/chrome/browser/gtk/options/general_page_gtk.h
index 3a072ac..143f447 100644
--- a/chrome/browser/gtk/options/general_page_gtk.h
+++ b/chrome/browser/gtk/options/general_page_gtk.h
@@ -14,6 +14,7 @@
 #include "chrome/browser/gtk/gtk_tree.h"
 #include "chrome/browser/gtk/options/managed_prefs_banner_gtk.h"
 #include "chrome/browser/options_page_base.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_member.h"
 #include "chrome/browser/search_engines/template_url_model_observer.h"
 #include "chrome/browser/shell_integration.h"
@@ -160,6 +161,8 @@ class GeneralPageGtk : public OptionsPageBase,
   // Tracks managed preference warning banner state.
   ManagedPrefsBannerGtk managed_prefs_banner_;
 
+  PrefChangeRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(GeneralPageGtk);
 };
 
diff --git a/chrome/browser/host_content_settings_map.cc b/chrome/browser/host_content_settings_map.cc
index cffe57e..4ac9f405 100644
--- a/chrome/browser/host_content_settings_map.cc
+++ b/chrome/browser/host_content_settings_map.cc
@@ -230,10 +230,11 @@ HostContentSettingsMap::HostContentSettingsMap(Profile* profile)
   // Read exceptions.
   ReadExceptions(false);
 
-  prefs->AddPrefObserver(prefs::kDefaultContentSettings, this);
-  prefs->AddPrefObserver(prefs::kContentSettingsPatterns, this);
-  prefs->AddPrefObserver(prefs::kBlockThirdPartyCookies, this);
-  prefs->AddPrefObserver(prefs::kBlockNonsandboxedPlugins, this);
+  pref_change_registrar_.Init(prefs);
+  pref_change_registrar_.Add(prefs::kDefaultContentSettings, this);
+  pref_change_registrar_.Add(prefs::kContentSettingsPatterns, this);
+  pref_change_registrar_.Add(prefs::kBlockThirdPartyCookies, this);
+  pref_change_registrar_.Add(prefs::kBlockNonsandboxedPlugins, this);
   notification_registrar_.Add(this, NotificationType::PROFILE_DESTROYED,
                               Source<Profile>(profile_));
 }
@@ -909,11 +910,7 @@ void HostContentSettingsMap::UnregisterObservers() {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
   if (!profile_)
     return;
-  PrefService* prefs = profile_->GetPrefs();
-  prefs->RemovePrefObserver(prefs::kDefaultContentSettings, this);
-  prefs->RemovePrefObserver(prefs::kContentSettingsPatterns, this);
-  prefs->RemovePrefObserver(prefs::kBlockThirdPartyCookies, this);
-  prefs->RemovePrefObserver(prefs::kBlockNonsandboxedPlugins, this);
+  pref_change_registrar_.RemoveAll();
   notification_registrar_.Remove(this, NotificationType::PROFILE_DESTROYED,
                                  Source<Profile>(profile_));
   profile_ = NULL;
diff --git a/chrome/browser/host_content_settings_map.h b/chrome/browser/host_content_settings_map.h
index ff9c8f0..7afb808 100644
--- a/chrome/browser/host_content_settings_map.h
+++ b/chrome/browser/host_content_settings_map.h
@@ -18,6 +18,7 @@
 #include "base/lock.h"
 #include "base/ref_counted.h"
 #include "chrome/browser/chrome_thread.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/content_settings.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
@@ -285,6 +286,7 @@ class HostContentSettingsMap
   Profile* profile_;
 
   NotificationRegistrar notification_registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   // Copies of the pref data, so that we can read it on the IO thread.
   ContentSettings default_content_settings_;
diff --git a/chrome/browser/host_zoom_map.cc b/chrome/browser/host_zoom_map.cc
index 0c1d96a..cb67a04 100644
--- a/chrome/browser/host_zoom_map.cc
+++ b/chrome/browser/host_zoom_map.cc
@@ -27,8 +27,10 @@ HostZoomMap::HostZoomMap(Profile* profile)
   // Don't observe pref changes (e.g. from sync) in Incognito; once we create
   // the incognito window it should have no further connection to the main
   // profile/prefs.
-  if (!profile_->IsOffTheRecord())
-    profile_->GetPrefs()->AddPrefObserver(prefs::kPerHostZoomLevels, this);
+  if (!profile_->IsOffTheRecord()) {
+    pref_change_registrar_.Init(profile_->GetPrefs());
+    pref_change_registrar_.Add(prefs::kPerHostZoomLevels, this);
+  }
 }
 
 void HostZoomMap::Load() {
@@ -128,7 +130,7 @@ void HostZoomMap::Shutdown() {
                     NotificationType::PROFILE_DESTROYED,
                     Source<Profile>(profile_));
   if (!profile_->IsOffTheRecord())
-    profile_->GetPrefs()->RemovePrefObserver(prefs::kPerHostZoomLevels, this);
+    pref_change_registrar_.RemoveAll();
   profile_ = NULL;
 }
 
diff --git a/chrome/browser/host_zoom_map.h b/chrome/browser/host_zoom_map.h
index caa60b7..3142024 100644
--- a/chrome/browser/host_zoom_map.h
+++ b/chrome/browser/host_zoom_map.h
@@ -15,6 +15,7 @@
 #include "base/basictypes.h"
 #include "base/lock.h"
 #include "base/ref_counted.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
 
@@ -83,6 +84,7 @@ class HostZoomMap : public NotificationObserver,
   bool updating_preferences_;
 
   NotificationRegistrar registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(HostZoomMap);
 };
diff --git a/chrome/browser/host_zoom_map_unittest.cc b/chrome/browser/host_zoom_map_unittest.cc
index e6b1f72..5d206e1 100644
--- a/chrome/browser/host_zoom_map_unittest.cc
+++ b/chrome/browser/host_zoom_map_unittest.cc
@@ -70,7 +70,9 @@ TEST_F(HostZoomMapTest, Load) {
 
 TEST_F(HostZoomMapTest, SetZoomLevel) {
   scoped_refptr<HostZoomMap> map(new HostZoomMap(&profile_));
-  prefs_->AddPrefObserver(prefs::kPerHostZoomLevels, &pref_observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(prefs_);
+  registrar.Add(prefs::kPerHostZoomLevels, &pref_observer_);
   SetPrefObserverExpectation();
   map->SetZoomLevel(url_, kZoomLevel);
   EXPECT_EQ(kZoomLevel, map->GetZoomLevel(url_));
@@ -84,19 +86,19 @@ TEST_F(HostZoomMapTest, SetZoomLevel) {
   map->SetZoomLevel(url_, 0);
   EXPECT_EQ(0, map->GetZoomLevel(url_));
   EXPECT_FALSE(dict->HasKey(host_));
-  prefs_->RemovePrefObserver(prefs::kPerHostZoomLevels, &pref_observer_);
 }
 
 TEST_F(HostZoomMapTest, ResetToDefaults) {
   scoped_refptr<HostZoomMap> map(new HostZoomMap(&profile_));
   map->SetZoomLevel(url_, kZoomLevel);
 
-  prefs_->AddPrefObserver(prefs::kPerHostZoomLevels, &pref_observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(prefs_);
+  registrar.Add(prefs::kPerHostZoomLevels, &pref_observer_);
   SetPrefObserverExpectation();
   map->ResetToDefaults();
   EXPECT_EQ(0, map->GetZoomLevel(url_));
   EXPECT_EQ(NULL, prefs_->GetDictionary(prefs::kPerHostZoomLevels));
-  prefs_->RemovePrefObserver(prefs::kPerHostZoomLevels, &pref_observer_);
 }
 
 TEST_F(HostZoomMapTest, ReloadOnPrefChange) {
diff --git a/chrome/browser/net/chrome_url_request_context.cc b/chrome/browser/net/chrome_url_request_context.cc
index f14958f..caefe49 100644
--- a/chrome/browser/net/chrome_url_request_context.cc
+++ b/chrome/browser/net/chrome_url_request_context.cc
@@ -526,8 +526,7 @@ ChromeURLRequestContext* FactoryForMedia::Create() {
 ChromeURLRequestContextGetter::ChromeURLRequestContextGetter(
     Profile* profile,
     ChromeURLRequestContextFactory* factory)
-  : prefs_(NULL),
-    factory_(factory),
+  : factory_(factory),
     url_request_context_(NULL) {
   DCHECK(factory);
 
@@ -539,7 +538,7 @@ ChromeURLRequestContextGetter::ChromeURLRequestContextGetter(
 ChromeURLRequestContextGetter::~ChromeURLRequestContextGetter() {
   CheckCurrentlyOnIOThread();
 
-  DCHECK(!prefs_) << "Probably didn't call CleanupOnUIThread";
+  DCHECK(registrar_.IsEmpty()) << "Probably didn't call CleanupOnUIThread";
 
   // Either we already transformed the factory into a URLRequestContext, or
   // we still have a pending factory.
@@ -652,13 +651,8 @@ ChromeURLRequestContextGetter::CreateOffTheRecordForExtensions(
 
 void ChromeURLRequestContextGetter::CleanupOnUIThread() {
   CheckCurrentlyOnMainThread();
-
-  if (prefs_) {
-    // Unregister for pref notifications.
-    prefs_->RemovePrefObserver(prefs::kAcceptLanguages, this);
-    prefs_->RemovePrefObserver(prefs::kDefaultCharset, this);
-    prefs_ = NULL;
-  }
+  // Unregister for pref notifications.
+  registrar_.RemoveAll();
 }
 
 void ChromeURLRequestContextGetter::OnNewExtensions(
@@ -710,10 +704,9 @@ void ChromeURLRequestContextGetter::Observe(
 void ChromeURLRequestContextGetter::RegisterPrefsObserver(Profile* profile) {
   CheckCurrentlyOnMainThread();
 
-  prefs_ = profile->GetPrefs();
-
-  prefs_->AddPrefObserver(prefs::kAcceptLanguages, this);
-  prefs_->AddPrefObserver(prefs::kDefaultCharset, this);
+  registrar_.Init(profile->GetPrefs());
+  registrar_.Add(prefs::kAcceptLanguages, this);
+  registrar_.Add(prefs::kDefaultCharset, this);
 }
 
 // static
diff --git a/chrome/browser/net/chrome_url_request_context.h b/chrome/browser/net/chrome_url_request_context.h
index 97997e3..52dc3f7 100644
--- a/chrome/browser/net/chrome_url_request_context.h
+++ b/chrome/browser/net/chrome_url_request_context.h
@@ -18,6 +18,7 @@
 #include "chrome/browser/host_zoom_map.h"
 #include "chrome/browser/io_thread.h"
 #include "chrome/browser/net/chrome_cookie_policy.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/net/url_request_context_getter.h"
@@ -367,8 +368,7 @@ class ChromeURLRequestContextGetter : public URLRequestContextGetter,
   void GetCookieStoreAsyncHelper(base::WaitableEvent* completion,
                                  net::CookieStore** result);
 
-  // Access only from the UI thread.
-  PrefService* prefs_;
+  PrefChangeRegistrar registrar_;
 
   // Deferred logic for creating a ChromeURLRequestContext.
   // Access only from the IO thread.
diff --git a/chrome/browser/notifications/desktop_notification_service.cc b/chrome/browser/notifications/desktop_notification_service.cc
index a467697..26afbed 100644
--- a/chrome/browser/notifications/desktop_notification_service.cc
+++ b/chrome/browser/notifications/desktop_notification_service.cc
@@ -209,6 +209,7 @@ DesktopNotificationService::DesktopNotificationService(Profile* profile,
     NotificationUIManager* ui_manager)
     : profile_(profile),
       ui_manager_(ui_manager) {
+  registrar_.Init(profile_->GetPrefs());
   InitPrefs();
   StartObserving();
 }
@@ -253,21 +254,15 @@ void DesktopNotificationService::InitPrefs() {
 
 void DesktopNotificationService::StartObserving() {
   if (!profile_->IsOffTheRecord()) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->AddPrefObserver(prefs::kDesktopNotificationDefaultContentSetting,
-                           this);
-    prefs->AddPrefObserver(prefs::kDesktopNotificationAllowedOrigins, this);
-    prefs->AddPrefObserver(prefs::kDesktopNotificationDeniedOrigins, this);
+    registrar_.Add(prefs::kDesktopNotificationDefaultContentSetting, this);
+    registrar_.Add(prefs::kDesktopNotificationAllowedOrigins, this);
+    registrar_.Add(prefs::kDesktopNotificationDeniedOrigins, this);
   }
 }
 
 void DesktopNotificationService::StopObserving() {
   if (!profile_->IsOffTheRecord()) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationDefaultContentSetting,
-                              this);
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationAllowedOrigins, this);
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationDeniedOrigins, this);
+    registrar_.RemoveAll();
   }
 }
 
diff --git a/chrome/browser/notifications/desktop_notification_service.h b/chrome/browser/notifications/desktop_notification_service.h
index d1a4ccc..2282cd2 100644
--- a/chrome/browser/notifications/desktop_notification_service.h
+++ b/chrome/browser/notifications/desktop_notification_service.h
@@ -11,6 +11,7 @@
 #include "base/basictypes.h"
 #include "base/string16.h"
 #include "chrome/browser/notifications/notification.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/content_settings.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
@@ -136,6 +137,8 @@ class DesktopNotificationService : public NotificationObserver {
   // UI for desktop toasts.
   NotificationUIManager* ui_manager_;
 
+  PrefChangeRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(DesktopNotificationService);
 };
 
diff --git a/chrome/browser/prefs/pref_change_registrar.cc b/chrome/browser/prefs/pref_change_registrar.cc
index dc8bb97..05372b1 100644
--- a/chrome/browser/prefs/pref_change_registrar.cc
+++ b/chrome/browser/prefs/pref_change_registrar.cc
@@ -9,16 +9,11 @@
 PrefChangeRegistrar::PrefChangeRegistrar() : service_(NULL) {}
 
 PrefChangeRegistrar::~PrefChangeRegistrar() {
-  if (service_) {
-    for (std::set<ObserverRegistration>::const_iterator it = observers_.begin();
-         it != observers_.end(); ++it) {
-      service_->RemovePrefObserver(it->first.c_str(), it->second);
-    }
-  }
+  RemoveAll();
 }
 
 void PrefChangeRegistrar::Init(PrefService* service) {
-  DCHECK(!service_);
+  DCHECK(IsEmpty() || service_ == service);
   service_ = service;
 }
 
@@ -51,3 +46,17 @@ void PrefChangeRegistrar::Remove(const char* path, NotificationObserver* obs) {
   service_->RemovePrefObserver(it->first.c_str(), it->second);
   observers_.erase(it);
 }
+
+void PrefChangeRegistrar::RemoveAll() {
+  if (service_) {
+    for (std::set<ObserverRegistration>::const_iterator it = observers_.begin();
+         it != observers_.end(); ++it) {
+      service_->RemovePrefObserver(it->first.c_str(), it->second);
+    }
+    observers_.clear();
+  }
+}
+
+bool PrefChangeRegistrar::IsEmpty() const {
+  return observers_.empty();
+}
diff --git a/chrome/browser/prefs/pref_change_registrar.h b/chrome/browser/prefs/pref_change_registrar.h
index cd8f5eb..773c556 100644
--- a/chrome/browser/prefs/pref_change_registrar.h
+++ b/chrome/browser/prefs/pref_change_registrar.h
@@ -23,7 +23,8 @@ class PrefChangeRegistrar {
   PrefChangeRegistrar();
   virtual ~PrefChangeRegistrar();
 
-  // Must be called before adding or removing observers.
+  // Must be called before adding or removing observers. Can be called more
+  // than once as long as the value of |service| doesn't change.
   void Init(PrefService* service);
 
   // Adds an pref observer for the specified pref |path| and |obs| observer
@@ -38,6 +39,12 @@ class PrefChangeRegistrar {
   void Remove(const char* path,
               NotificationObserver* obs);
 
+  // Removes all observers that have been previously added with a call to Add.
+  void RemoveAll();
+
+  // Returns true if no pref observers are registered.
+  bool IsEmpty() const;
+
  private:
   typedef std::pair<std::string, NotificationObserver*> ObserverRegistration;
 
diff --git a/chrome/browser/prefs/pref_change_registrar_unittest.cc b/chrome/browser/prefs/pref_change_registrar_unittest.cc
index 4d7f747..8096ee6 100644
--- a/chrome/browser/prefs/pref_change_registrar_unittest.cc
+++ b/chrome/browser/prefs/pref_change_registrar_unittest.cc
@@ -63,6 +63,7 @@ TEST_F(PrefChangeRegistrarTest, AddAndRemove) {
               AddPrefObserver(Eq(std::string("test.pref.2")), observer()));
   registrar.Add("test.pref.1", observer());
   registrar.Add("test.pref.2", observer());
+  EXPECT_FALSE(registrar.IsEmpty());
 
   // Test removing.
   Mock::VerifyAndClearExpectations(service());
@@ -72,6 +73,11 @@ TEST_F(PrefChangeRegistrarTest, AddAndRemove) {
               RemovePrefObserver(Eq(std::string("test.pref.2")), observer()));
   registrar.Remove("test.pref.1", observer());
   registrar.Remove("test.pref.2", observer());
+  EXPECT_TRUE(registrar.IsEmpty());
+
+  // Explicitly check the expectations now to make sure that the Removes
+  // worked (rather than the registrar destructor doing the work).
+  Mock::VerifyAndClearExpectations(service());
 }
 
 TEST_F(PrefChangeRegistrarTest, AutoRemove) {
@@ -83,8 +89,33 @@ TEST_F(PrefChangeRegistrarTest, AutoRemove) {
               AddPrefObserver(Eq(std::string("test.pref.1")), observer()));
   registrar.Add("test.pref.1", observer());
   Mock::VerifyAndClearExpectations(service());
+  EXPECT_FALSE(registrar.IsEmpty());
 
   // Test auto-removing.
   EXPECT_CALL(*service(),
               RemovePrefObserver(Eq(std::string("test.pref.1")), observer()));
 }
+
+TEST_F(PrefChangeRegistrarTest, RemoveAll) {
+  PrefChangeRegistrar registrar;
+  registrar.Init(service());
+
+  EXPECT_CALL(*service(),
+              AddPrefObserver(Eq(std::string("test.pref.1")), observer()));
+  EXPECT_CALL(*service(),
+              AddPrefObserver(Eq(std::string("test.pref.2")), observer()));
+  registrar.Add("test.pref.1", observer());
+  registrar.Add("test.pref.2", observer());
+  Mock::VerifyAndClearExpectations(service());
+
+  EXPECT_CALL(*service(),
+              RemovePrefObserver(Eq(std::string("test.pref.1")), observer()));
+  EXPECT_CALL(*service(),
+              RemovePrefObserver(Eq(std::string("test.pref.2")), observer()));
+  registrar.RemoveAll();
+  EXPECT_TRUE(registrar.IsEmpty());
+
+  // Explicitly check the expectations now to make sure that the RemoveAll
+  // worked (rather than the registrar destructor doing the work).
+  Mock::VerifyAndClearExpectations(service());
+}
diff --git a/chrome/browser/prefs/pref_service.h b/chrome/browser/prefs/pref_service.h
index 450c6c1..5cedd52 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -19,9 +19,14 @@
 
 class FilePath;
 class NotificationObserver;
+class PrefChangeObserver;
 class PrefNotifier;
 class Profile;
 
+namespace subtle {
+  class PrefMemberBase;
+};
+
 class PrefService : public NonThreadSafe {
  public:
   // A helper class to store all the information associated with a preference.
@@ -161,11 +166,6 @@ class PrefService : public NonThreadSafe {
   const DictionaryValue* GetDictionary(const char* path) const;
   const ListValue* GetList(const char* path) const;
 
-  // If the pref at the given path changes, we call the observer's Observe
-  // method with NOTIFY_PREF_CHANGED.
-  virtual void AddPrefObserver(const char* path, NotificationObserver* obs);
-  virtual void RemovePrefObserver(const char* path, NotificationObserver* obs);
-
   // Removes a user pref and restores the pref to its default value.
   void ClearPref(const char* path);
 
@@ -229,6 +229,22 @@ class PrefService : public NonThreadSafe {
   scoped_ptr<PrefNotifier> pref_notifier_;
 
  private:
+  // Registration of pref change observers must be done using the
+  // PrefChangeRegistrar, which is declared as a friend here to grant it
+  // access to the otherwise protected members Add/RemovePrefObserver.
+  // PrefMember registers for preferences changes notification directly to
+  // avoid the storage overhead of the registrar, so its base class must be
+  // declared as a friend, too.
+  friend class PrefChangeRegistrar;
+  friend class subtle::PrefMemberBase;
+
+  // If the pref at the given path changes, we call the observer's Observe
+  // method with NOTIFY_PREF_CHANGED. Note that observers should not call
+  // these methods directly but rather use a PrefChangeRegistrar to make sure
+  // the observer gets cleaned up properly.
+  virtual void AddPrefObserver(const char* path, NotificationObserver* obs);
+  virtual void RemovePrefObserver(const char* path, NotificationObserver* obs);
+
   // Add a preference to the PreferenceMap.  If the pref already exists, return
   // false.  This method takes ownership of |default_value|.
   void RegisterPreference(const char* path, Value* default_value);
diff --git a/chrome/browser/prefs/pref_service_unittest.cc b/chrome/browser/prefs/pref_service_unittest.cc
index 461f108..d62679d 100644
--- a/chrome/browser/prefs/pref_service_unittest.cc
+++ b/chrome/browser/prefs/pref_service_unittest.cc
@@ -8,6 +8,7 @@
 #include "base/scoped_ptr.h"
 #include "base/values.h"
 #include "chrome/browser/prefs/dummy_pref_store.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_value_store.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/notification_observer_mock.h"
@@ -94,7 +95,10 @@ TEST(PrefServiceTest, NoObserverFire) {
 
   const std::string new_pref_value("http://www.google.com/");
   TestPrefObserver obs(&prefs, pref_name, new_pref_value);
-  prefs.AddPrefObserver(pref_name, &obs);
+
+  PrefChangeRegistrar registrar;
+  registrar.Init(&prefs);
+  registrar.Add(pref_name, &obs);
   // This should fire the checks in TestPrefObserver::Observe.
   prefs.SetString(pref_name, new_pref_value);
 
@@ -116,9 +120,6 @@ TEST(PrefServiceTest, NoObserverFire) {
   obs.Reset("");
   prefs.ClearPref(pref_name);
   EXPECT_FALSE(obs.observer_fired());
-
-  // Ok, clean up.
-  prefs.RemovePrefObserver(pref_name, &obs);
 }
 
 TEST(PrefServiceTest, HasPrefPath) {
@@ -148,7 +149,9 @@ TEST(PrefServiceTest, Observers) {
 
   const std::string new_pref_value("http://www.google.com/");
   TestPrefObserver obs(&prefs, pref_name, new_pref_value);
-  prefs.AddPrefObserver(pref_name, &obs);
+  PrefChangeRegistrar registrar;
+  registrar.Init(&prefs);
+  registrar.Add(pref_name, &obs);
   // This should fire the checks in TestPrefObserver::Observe.
   prefs.SetString(pref_name, new_pref_value);
 
@@ -159,23 +162,20 @@ TEST(PrefServiceTest, Observers) {
   const std::string new_pref_value2("http://www.youtube.com/");
   obs.Reset(new_pref_value2);
   TestPrefObserver obs2(&prefs, pref_name, new_pref_value2);
-  prefs.AddPrefObserver(pref_name, &obs2);
+  registrar.Add(pref_name, &obs2);
   // This should fire the checks in obs and obs2.
   prefs.SetString(pref_name, new_pref_value2);
   EXPECT_TRUE(obs.observer_fired());
   EXPECT_TRUE(obs2.observer_fired());
 
   // Make sure obs2 still works after removing obs.
-  prefs.RemovePrefObserver(pref_name, &obs);
+  registrar.Remove(pref_name, &obs);
   obs.Reset("");
   obs2.Reset(new_pref_value);
   // This should only fire the observer in obs2.
   prefs.SetString(pref_name, new_pref_value);
   EXPECT_FALSE(obs.observer_fired());
   EXPECT_TRUE(obs2.observer_fired());
-
-  // Ok, clean up.
-  prefs.RemovePrefObserver(pref_name, &obs2);
 }
 
 class PrefServiceSetValueTest : public testing::Test {
@@ -211,7 +211,11 @@ TEST_F(PrefServiceSetValueTest, SetStringValue) {
   const char default_string[] = "default";
   scoped_ptr<Value> default_value(Value::CreateStringValue(default_string));
   prefs_.RegisterStringPref(name_, default_string);
-  prefs_.AddPrefObserver(name_, &observer_);
+
+  PrefChangeRegistrar registrar;
+  registrar.Init(&prefs_);
+  registrar.Add(name_, &observer_);
+
   // Changing the controlling store from default to user triggers notification.
   SetExpectPrefChanged();
   prefs_.Set(name_, *default_value);
@@ -225,13 +229,13 @@ TEST_F(PrefServiceSetValueTest, SetStringValue) {
   SetExpectPrefChanged();
   prefs_.Set(name_, *new_value);
   EXPECT_EQ(value_, prefs_.GetString(name_));
-
-  prefs_.RemovePrefObserver(name_, &observer_);
 }
 
 TEST_F(PrefServiceSetValueTest, SetDictionaryValue) {
   prefs_.RegisterDictionaryPref(name_);
-  prefs_.AddPrefObserver(name_, &observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(&prefs_);
+  registrar.Add(name_, &observer_);
 
   // Dictionary values are special: setting one to NULL is the same as clearing
   // the user value, allowing the NULL default to take (or keep) control.
@@ -259,13 +263,13 @@ TEST_F(PrefServiceSetValueTest, SetDictionaryValue) {
   Mock::VerifyAndClearExpectations(&observer_);
   dict = prefs_.GetMutableDictionary(name_);
   EXPECT_EQ(0U, dict->size());
-
-  prefs_.RemovePrefObserver(name_, &observer_);
 }
 
 TEST_F(PrefServiceSetValueTest, SetListValue) {
   prefs_.RegisterListPref(name_);
-  prefs_.AddPrefObserver(name_, &observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(&prefs_);
+  registrar.Add(name_, &observer_);
 
   // List values are special: setting one to NULL is the same as clearing the
   // user value, allowing the NULL default to take (or keep) control.
@@ -293,6 +297,4 @@ TEST_F(PrefServiceSetValueTest, SetListValue) {
   Mock::VerifyAndClearExpectations(&observer_);
   list = prefs_.GetMutableList(name_);
   EXPECT_EQ(0U, list->GetSize());
-
-  prefs_.RemovePrefObserver(name_, &observer_);
 }
diff --git a/chrome/browser/prefs/pref_set_observer.cc b/chrome/browser/prefs/pref_set_observer.cc
index a4ecf6f..dd067d3 100644
--- a/chrome/browser/prefs/pref_set_observer.cc
+++ b/chrome/browser/prefs/pref_set_observer.cc
@@ -11,23 +11,19 @@ PrefSetObserver::PrefSetObserver(PrefService* pref_service,
                                  NotificationObserver* observer)
     : pref_service_(pref_service),
       observer_(observer) {
-}
-
-PrefSetObserver::~PrefSetObserver() {
-  for (PrefSet::const_iterator i(prefs_.begin()); i != prefs_.end(); ++i)
-    pref_service_->RemovePrefObserver(i->c_str(), this);
+  registrar_.Init(pref_service);
 }
 
 void PrefSetObserver::AddPref(const std::string& pref) {
   if (!prefs_.count(pref) && pref_service_->FindPreference(pref.c_str())) {
     prefs_.insert(pref);
-    pref_service_->AddPrefObserver(pref.c_str(), this);
+    registrar_.Add(pref.c_str(), this);
   }
 }
 
 void PrefSetObserver::RemovePref(const std::string& pref) {
   if (prefs_.erase(pref))
-    pref_service_->RemovePrefObserver(pref.c_str(), this);
+    registrar_.Remove(pref.c_str(), this);
 }
 
 bool PrefSetObserver::IsObserved(const std::string& pref) {
diff --git a/chrome/browser/prefs/pref_set_observer.h b/chrome/browser/prefs/pref_set_observer.h
index beaec01..ff350df 100644
--- a/chrome/browser/prefs/pref_set_observer.h
+++ b/chrome/browser/prefs/pref_set_observer.h
@@ -10,6 +10,7 @@
 
 #include "base/basictypes.h"
 #include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/notification_observer.h"
 
 // Observes the state of a set of preferences and allows to query their combined
@@ -19,7 +20,7 @@ class PrefSetObserver : public NotificationObserver {
   // Initialize with an empty set of preferences.
   PrefSetObserver(PrefService* pref_service,
                   NotificationObserver* observer);
-  virtual ~PrefSetObserver();
+  virtual ~PrefSetObserver() {}
 
   // Add a |pref| to the set of preferences to observe.
   void AddPref(const std::string& pref);
@@ -51,6 +52,7 @@ class PrefSetObserver : public NotificationObserver {
   PrefSet prefs_;
 
   PrefService* pref_service_;
+  PrefChangeRegistrar registrar_;
   NotificationObserver* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefSetObserver);
diff --git a/chrome/browser/profile_impl.cc b/chrome/browser/profile_impl.cc
index fb5f501..ad2b405 100644
--- a/chrome/browser/profile_impl.cc
+++ b/chrome/browser/profile_impl.cc
@@ -290,9 +290,10 @@ ProfileImpl::ProfileImpl(const FilePath& path)
       &ProfileImpl::EnsureSessionServiceCreated);
 
   PrefService* prefs = GetPrefs();
-  prefs->AddPrefObserver(prefs::kSpellCheckDictionary, this);
-  prefs->AddPrefObserver(prefs::kEnableSpellCheck, this);
-  prefs->AddPrefObserver(prefs::kEnableAutoSpellCorrect, this);
+  pref_change_registrar_.Init(prefs);
+  pref_change_registrar_.Add(prefs::kSpellCheckDictionary, this);
+  pref_change_registrar_.Add(prefs::kEnableSpellCheck, this);
+  pref_change_registrar_.Add(prefs::kEnableAutoSpellCorrect, this);
 
 #if defined(OS_MACOSX)
   // If the profile directory doesn't already have a cache directory and it
@@ -499,11 +500,8 @@ ProfileImpl::~ProfileImpl() {
   // The theme provider provides bitmaps to whoever wants them.
   theme_provider_.reset();
 
-  // Remove pref observers.
-  PrefService* prefs = GetPrefs();
-  prefs->RemovePrefObserver(prefs::kSpellCheckDictionary, this);
-  prefs->RemovePrefObserver(prefs::kEnableSpellCheck, this);
-  prefs->RemovePrefObserver(prefs::kEnableAutoSpellCorrect, this);
+  // Remove pref observers
+  pref_change_registrar_.RemoveAll();
 
   // Delete the NTP resource cache so we can unregister pref observers.
   ntp_resource_cache_.reset();
diff --git a/chrome/browser/profile_impl.h b/chrome/browser/profile_impl.h
index 9331d34..f324fbd 100644
--- a/chrome/browser/profile_impl.h
+++ b/chrome/browser/profile_impl.h
@@ -13,6 +13,7 @@
 #include "base/scoped_ptr.h"
 #include "base/timer.h"
 #include "chrome/browser/profile.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/spellcheck_host_observer.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
@@ -144,6 +145,7 @@ class ProfileImpl : public Profile,
   }
 
   NotificationRegistrar registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   FilePath path_;
   FilePath base_cache_path_;
diff --git a/chrome/browser/sync/glue/preference_change_processor.cc b/chrome/browser/sync/glue/preference_change_processor.cc
index ec0eeb3..874f786 100644
--- a/chrome/browser/sync/glue/preference_change_processor.cc
+++ b/chrome/browser/sync/glue/preference_change_processor.cc
@@ -195,6 +195,7 @@ Value* PreferenceChangeProcessor::ReadPreference(
 void PreferenceChangeProcessor::StartImpl(Profile* profile) {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
   pref_service_ = profile->GetPrefs();
+  registrar_.Init(pref_service_);
   StartObserving();
 }
 
@@ -210,7 +211,7 @@ void PreferenceChangeProcessor::StartObserving() {
   for (std::set<std::string>::const_iterator it =
       model_associator_->synced_preferences().begin();
       it != model_associator_->synced_preferences().end(); ++it) {
-    pref_service_->AddPrefObserver((*it).c_str(), this);
+    registrar_.Add((*it).c_str(), this);
   }
 }
 
@@ -219,7 +220,7 @@ void PreferenceChangeProcessor::StopObserving() {
   for (std::set<std::string>::const_iterator it =
       model_associator_->synced_preferences().begin();
       it != model_associator_->synced_preferences().end(); ++it) {
-    pref_service_->RemovePrefObserver((*it).c_str(), this);
+    registrar_.Remove((*it).c_str(), this);
   }
 }
 
diff --git a/chrome/browser/sync/glue/preference_change_processor.h b/chrome/browser/sync/glue/preference_change_processor.h
index cb25511..1ef88da 100644
--- a/chrome/browser/sync/glue/preference_change_processor.h
+++ b/chrome/browser/sync/glue/preference_change_processor.h
@@ -8,6 +8,7 @@
 
 #include <string>
 
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/sync/engine/syncapi.h"
 #include "chrome/browser/sync/glue/change_processor.h"
@@ -60,6 +61,8 @@ class PreferenceChangeProcessor : public ChangeProcessor,
   // Whether we are currently processing a preference change notification.
   bool processing_pref_change_;
 
+  PrefChangeRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(PreferenceChangeProcessor);
 };
 
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index 5edfb32..8ed1017 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -399,9 +399,10 @@ TabContents::TabContents(Profile* profile,
 
   // Register for notifications about all interested prefs change.
   PrefService* prefs = profile->GetPrefs();
+  pref_change_registrar_.Init(prefs);
   if (prefs) {
     for (int i = 0; i < kPrefsToObserveLength; ++i)
-      prefs->AddPrefObserver(kPrefsToObserve[i], this);
+      pref_change_registrar_.Add(kPrefsToObserve[i], this);
   }
 
   // Register for notifications about URL starredness changing on any profile.
@@ -441,13 +442,7 @@ TabContents::~TabContents() {
 
   // We don't want any notifications while we're running our destructor.
   registrar_.RemoveAll();
-
-  // Unregister the notifications of all observed prefs change.
-  PrefService* prefs = profile()->GetPrefs();
-  if (prefs) {
-    for (int i = 0; i < kPrefsToObserveLength; ++i)
-      prefs->RemovePrefObserver(kPrefsToObserve[i], this);
-  }
+  pref_change_registrar_.RemoveAll();
 
   NotifyDisconnected();
   hung_renderer_dialog::HideForTabContents(this);
diff --git a/chrome/browser/tab_contents/tab_contents.h b/chrome/browser/tab_contents/tab_contents.h
index 90ded2e..d37aab8 100644
--- a/chrome/browser/tab_contents/tab_contents.h
+++ b/chrome/browser/tab_contents/tab_contents.h
@@ -24,6 +24,7 @@
 #include "chrome/browser/find_bar_controller.h"
 #include "chrome/browser/find_notification_details.h"
 #include "chrome/browser/jsmessage_box_client.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/password_manager/password_manager_delegate.h"
 #include "chrome/browser/renderer_host/render_view_host_delegate.h"
 #include "chrome/browser/tab_contents/constrained_window.h"
@@ -1057,6 +1058,9 @@ class TabContents : public PageNavigator,
   // Registers and unregisters us for notifications.
   NotificationRegistrar registrar_;
 
+  // Registers and unregisters for pref notifications.
+  PrefChangeRegistrar pref_change_registrar_;
+
   // Handles print preview and print job for this contents.
   scoped_ptr<printing::PrintViewManager> printing_;
 
diff --git a/chrome/browser/translate/translate_manager.cc b/chrome/browser/translate/translate_manager.cc
index 1ea9fad..336eb2a 100644
--- a/chrome/browser/translate/translate_manager.cc
+++ b/chrome/browser/translate/translate_manager.cc
@@ -248,7 +248,7 @@ void TranslateManager::Observe(NotificationType type,
       // We should know about this profile since we are listening for
       // notifications on it.
       DCHECK(count > 0);
-      profile->GetPrefs()->RemovePrefObserver(prefs::kAcceptLanguages, this);
+      pref_change_registrar_.Remove(prefs::kAcceptLanguages, this);
       break;
     }
     case NotificationType::PREF_CHANGED: {
@@ -341,6 +341,8 @@ void TranslateManager::InitiateTranslation(TabContents* tab,
   if (!prefs->GetBoolean(prefs::kEnableTranslate))
     return;
 
+  pref_change_registrar_.Init(prefs);
+
   // Allow disabling of translate from the command line to assist with
   // automated browser testing.
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableTranslate))
@@ -533,7 +535,7 @@ bool TranslateManager::IsAcceptLanguage(TabContents* tab,
     notification_registrar_.Add(this, NotificationType::PROFILE_DESTROYED,
                                 Source<Profile>(tab->profile()));
     // Also start listening for changes in the accept languages.
-    tab->profile()->GetPrefs()->AddPrefObserver(prefs::kAcceptLanguages, this);
+    pref_change_registrar_.Add(prefs::kAcceptLanguages, this);
 
     iter = accept_languages_.find(pref_service);
   }
diff --git a/chrome/browser/translate/translate_manager.h b/chrome/browser/translate/translate_manager.h
index adec281..3ddcabf 100644
--- a/chrome/browser/translate/translate_manager.h
+++ b/chrome/browser/translate/translate_manager.h
@@ -14,6 +14,7 @@
 #include "base/lazy_instance.h"
 #include "base/singleton.h"
 #include "base/task.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/common/net/url_fetcher.h"
 #include "chrome/common/notification_observer.h"
 #include "chrome/common/notification_registrar.h"
@@ -153,6 +154,7 @@ class TranslateManager : public NotificationObserver,
       TabContents* tab);
 
   NotificationRegistrar notification_registrar_;
+  PrefChangeRegistrar pref_change_registrar_;
 
   // A map that associates a profile with its parsed "accept languages".
   typedef std::set<std::string> LanguageSet;
diff --git a/chrome/browser/translate/translate_manager_unittest.cc b/chrome/browser/translate/translate_manager_unittest.cc
index 8f2b801..f578b3f 100644
--- a/chrome/browser/translate/translate_manager_unittest.cc
+++ b/chrome/browser/translate/translate_manager_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_dll_resource.h"
 #include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/renderer_host/mock_render_process_host.h"
 #include "chrome/browser/tab_contents/navigation_controller.h"
 #include "chrome/browser/tab_contents/render_view_context_menu.h"
@@ -851,8 +852,10 @@ TEST_F(TranslateManagerTest, NeverTranslateLanguagePref) {
 
   // Select never translate this language.
   PrefService* prefs = contents()->profile()->GetPrefs();
-  prefs->AddPrefObserver(TranslatePrefs::kPrefTranslateLanguageBlacklist,
-                         &pref_observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(prefs);
+  registrar.Add(TranslatePrefs::kPrefTranslateLanguageBlacklist,
+                &pref_observer_);
   TranslatePrefs translate_prefs(prefs);
   EXPECT_FALSE(translate_prefs.IsLanguageBlacklisted("fr"));
   EXPECT_TRUE(translate_prefs.CanTranslate(prefs, "fr", url));
@@ -881,8 +884,6 @@ TEST_F(TranslateManagerTest, NeverTranslateLanguagePref) {
 
   // There should be a translate infobar.
   EXPECT_TRUE(GetTranslateInfoBar() != NULL);
-  prefs->RemovePrefObserver(TranslatePrefs::kPrefTranslateLanguageBlacklist,
-                            &pref_observer_);
 }
 
 // Tests the "Never translate this site" pref.
@@ -897,8 +898,10 @@ TEST_F(TranslateManagerTest, NeverTranslateSitePref) {
 
   // Select never translate this site.
   PrefService* prefs = contents()->profile()->GetPrefs();
-  prefs->AddPrefObserver(TranslatePrefs::kPrefTranslateSiteBlacklist,
-                         &pref_observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(prefs);
+  registrar.Add(TranslatePrefs::kPrefTranslateSiteBlacklist,
+                &pref_observer_);
   TranslatePrefs translate_prefs(prefs);
   EXPECT_FALSE(translate_prefs.IsSiteBlacklisted(host));
   EXPECT_TRUE(translate_prefs.CanTranslate(prefs, "fr", url));
@@ -927,16 +930,16 @@ TEST_F(TranslateManagerTest, NeverTranslateSitePref) {
 
   // There should be a translate infobar.
   EXPECT_TRUE(GetTranslateInfoBar() != NULL);
-  prefs->RemovePrefObserver(TranslatePrefs::kPrefTranslateSiteBlacklist,
-                            &pref_observer_);
 }
 
 // Tests the "Always translate this language" pref.
 TEST_F(TranslateManagerTest, AlwaysTranslateLanguagePref) {
   // Select always translate French to English.
   PrefService* prefs = contents()->profile()->GetPrefs();
-  prefs->AddPrefObserver(TranslatePrefs::kPrefTranslateWhitelists,
-                         &pref_observer_);
+  PrefChangeRegistrar registrar;
+  registrar.Init(prefs);
+  registrar.Add(TranslatePrefs::kPrefTranslateWhitelists,
+                &pref_observer_);
   TranslatePrefs translate_prefs(prefs);
   SetPrefObserverExpectation(TranslatePrefs::kPrefTranslateWhitelists);
   translate_prefs.WhitelistLanguagePair("fr", "en");
@@ -985,8 +988,6 @@ TEST_F(TranslateManagerTest, AlwaysTranslateLanguagePref) {
   infobar = GetTranslateInfoBar();
   ASSERT_TRUE(infobar != NULL);
   EXPECT_EQ(TranslateInfoBarDelegate::BEFORE_TRANSLATE, infobar->type());
-  prefs->RemovePrefObserver(TranslatePrefs::kPrefTranslateWhitelists,
-                            &pref_observer_);
 }
 
 // Context menu.
diff --git a/chrome/browser/views/options/general_page_view.cc b/chrome/browser/views/options/general_page_view.cc
index 8bf838f..f340967 100644
--- a/chrome/browser/views/options/general_page_view.cc
+++ b/chrome/browser/views/options/general_page_view.cc
@@ -202,9 +202,6 @@ GeneralPageView::GeneralPageView(Profile* profile)
 }
 
 GeneralPageView::~GeneralPageView() {
-  profile()->GetPrefs()->RemovePrefObserver(prefs::kRestoreOnStartup, this);
-  profile()->GetPrefs()->RemovePrefObserver(
-      prefs::kURLsToRestoreOnStartup, this);
   if (startup_custom_pages_table_)
     startup_custom_pages_table_->SetModel(NULL);
   default_browser_worker_->ObserverDestroyed();
@@ -341,8 +338,9 @@ void GeneralPageView::InitControlLayout() {
 #endif
 
   // Register pref observers that update the controls when a pref changes.
-  profile()->GetPrefs()->AddPrefObserver(prefs::kRestoreOnStartup, this);
-  profile()->GetPrefs()->AddPrefObserver(prefs::kURLsToRestoreOnStartup, this);
+  registrar_.Init(profile()->GetPrefs());
+  registrar_.Add(prefs::kRestoreOnStartup, this);
+  registrar_.Add(prefs::kURLsToRestoreOnStartup, this);
 
   new_tab_page_is_home_page_.Init(prefs::kHomePageIsNewTabPage,
       profile()->GetPrefs(), this);
diff --git a/chrome/browser/views/options/general_page_view.h b/chrome/browser/views/options/general_page_view.h
index 93a7af5..f2b126f 100644
--- a/chrome/browser/views/options/general_page_view.h
+++ b/chrome/browser/views/options/general_page_view.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_VIEWS_OPTIONS_GENERAL_PAGE_VIEW_H_
 #pragma once
 
+#include "chrome/browser/prefs/pref_change_registrar.h"
 #include "chrome/browser/prefs/pref_member.h"
 #include "chrome/browser/shell_integration.h"
 #include "chrome/browser/views/options/options_page_view.h"
@@ -156,6 +157,8 @@ class GeneralPageView : public OptionsPageView,
   // The helper object that performs default browser set/check tasks.
   scoped_refptr<ShellIntegration::DefaultBrowserWorker> default_browser_worker_;
 
+  PrefChangeRegistrar registrar_;
+
   DISALLOW_COPY_AND_ASSIGN(GeneralPageView);
 };