MD Settings: avoid double pref observation on Startup Pages

chrome/browser/ui/webui/settings/people_handler.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_SETTINGS_PEOPLE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_PEOPLE_HANDLER_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/scoped_observer.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile_attributes_storage.h"
 #include "chrome/browser/sync/sync_startup_tracker.h"
+#include "chrome/browser/ui/webui/settings/md_settings_ui.h"
 #include "chrome/browser/ui/webui/signin/login_ui_service.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "components/signin/core/browser/signin_manager_base.h"
 #include "components/sync_driver/sync_service_observer.h"
-#include "content/public/browser/web_ui_message_handler.h"
 
 #if defined(OS_CHROMEOS)
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #endif
 
 class LoginUIService;
 class ProfileSyncService;
 class SigninManagerBase;
 
 namespace content {
 class WebContents;
 class WebUI;
 }
 
 namespace signin_metrics {
 enum class AccessPoint;
 }
 
 namespace settings {
 
-class PeopleHandler : public content::WebUIMessageHandler,
+class PeopleHandler : public SettingsPageUIHandler,

[michaelpg, 2016/03/11 01:16:54]

why?

[Dan Beam, 2016/03/11 05:39:06]

I restricted AddSettingsPageUIHandler() to take a SettingsPageUIHandler* instead
of a content::WebUIMessageHandler* so that every handler has a
RenderViewReused() method

                       public SigninManagerBase::Observer,
                       public SyncStartupTracker::Observer,
                       public LoginUIService::LoginUI,
                       public sync_driver::SyncServiceObserver,
 #if defined(OS_CHROMEOS)
                       public content::NotificationObserver,
 #endif
                       public ProfileAttributesStorage::Observer {
  public:
   explicit PeopleHandler(Profile* profile);
   ~PeopleHandler() override;
 
-  // content::WebUIMessageHandler implementation.
+  // SettingsPageUIHandler implementation.
   void RegisterMessages() override;
 
   // SyncStartupTracker::Observer implementation.
   void SyncStartupCompleted() override;
   void SyncStartupFailed() override;
 
   // LoginUIService::LoginUI implementation.
   void FocusUI() override;
   void CloseUI() override;
 
@@ skipping 153 matching lines @@
 
   // Manages observer lifetime.
   ScopedObserver<ProfileSyncService, PeopleHandler> sync_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(PeopleHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_PEOPLE_HANDLER_H_