Get rid of sync_preferences::SyncedPrefObserver inheritance.

chrome/browser/ui/ash/launcher/chrome_launcher_controller_impl_unittest.cc

 // Copyright 2013 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/ash/launcher/chrome_launcher_controller_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <map>
@@ skipping 814 matching lines @@
 
   void UninstallArcApps() {
     arc_test_.app_instance()->RefreshAppList();
     arc_test_.app_instance()->SendRefreshAppList(
         std::vector<arc::mojom::AppInfo>());
   }
 
   void EnableArc(bool enable) {
     enable ? arc_test_.arc_session_manager()->EnableArc()
            : arc_test_.arc_session_manager()->DisableArc();
-    arc_test_.arc_session_manager()->OnSyncedPrefChanged(prefs::kArcEnabled,
-                                                         false);
     base::RunLoop().RunUntilIdle();
   }
 
   void EnableTabletMode(bool enable) {
     ash::MaximizeModeController* controller =
         ash::WmShell::Get()->maximize_mode_controller();
     controller->EnableMaximizeModeWindowManager(enable);
   }
 
   void ValidateArcState(bool arc_enabled,
@@ skipping 3437 matching lines @@
   EXPECT_EQ(ash::SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS,
             shelf_controller->auto_hide());
   EXPECT_EQ(2u, shelf_controller->auto_hide_change_count());
 
   PrefService* prefs = profile()->GetTestingPrefService();
   EXPECT_EQ("Left", prefs->GetString(prefs::kShelfAlignmentLocal));
   EXPECT_EQ("Left", prefs->GetString(prefs::kShelfAlignment));
   EXPECT_EQ("Always", prefs->GetString(prefs::kShelfAutoHideBehaviorLocal));
   EXPECT_EQ("Always", prefs->GetString(prefs::kShelfAutoHideBehavior));
 }