Update AutoImport to import nothing by default (in absence of policy and master_prefs).

chrome/browser/prefs/chrome_pref_service_factory.h

 // 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.
 
 #ifndef CHROME_BROWSER_PREFS_CHROME_PREF_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_PREFS_CHROME_PREF_SERVICE_FACTORY_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
@@ skipping 70 matching lines @@
     bool async);
 
 // Call before startup tasks kick in to ignore the presence of a domain when
 // determining the active SettingsEnforcement group. For testing only.
 void DisableDomainCheckForTesting();
 
 // Initializes the preferences for the profile at |profile_path| with the
 // preference values in |master_prefs|. Returns true on success.
 bool InitializePrefsFromMasterPrefs(
     const base::FilePath& profile_path,
-    const base::DictionaryValue& master_prefs);
+    std::unique_ptr<base::DictionaryValue> master_prefs);
 
 // Retrieves the time of the last preference reset event, if any, for the
 // provided profile. If no reset has occurred, returns a null |Time|.
 base::Time GetResetTime(Profile* profile);
 
 // Clears the time of the last preference reset event, if any, for the provided
 // profile.
 void ClearResetTime(Profile* profile);
 
 // Register user prefs used by chrome preference system.
 void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
 }  // namespace chrome_prefs
 
 #endif  // CHROME_BROWSER_PREFS_CHROME_PREF_SERVICE_FACTORY_H_