Explicitly ShutdownOnUIThread the HostContentSettingsMap when destroying the Profile.

chrome/browser/content_settings/content_settings_provider.h

 // Copyright (c) 2011 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.
 
 // Interface for objects providing content setting rules.
 
 #ifndef CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_
 #define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_
 #pragma once
 
@@ skipping 24 matching lines @@
   // Notifies the provider that the host content settings map would like to
   // update the default setting for the given |content_type|. The provider may
   // ignore this.
   virtual void UpdateDefaultSetting(ContentSettingsType content_type,
                                     ContentSetting setting) = 0;
 
   // True if the default setting for the |content_type| is policy managed, i.e.,
   // there shouldn't be any UI shown to modify this setting.
   virtual bool DefaultSettingIsManaged(
       ContentSettingsType content_type) const = 0;
+
+  virtual void ShutdownOnUIThread() = 0;
 };
 
 class ProviderInterface {
  public:
   struct Rule {
     Rule();
     Rule(const ContentSettingsPattern& primary_pattern,
          const ContentSettingsPattern& secondary_pattern,
          ContentSetting setting);
 
@@ skipping 41 matching lines @@
   // must be non-empty.
   //
   // This may be called on any thread.
   virtual void GetAllContentSettingsRules(
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       Rules* content_setting_rules) const = 0;
 
   // Resets all content settings for the given |content_type| to
   // CONTENT_SETTING_DEFAULT. For content types that require a resource
-  // identifier all content settings for any resource identifieres of the given
+  // identifier all content settings for any resource identifiers of the given
   // |content_type| will be reset to CONTENT_SETTING_DEFAULT.
   //
   // This should only be called on the UI thread, and not after
   // ShutdownOnUIThread has been called.
   virtual void ClearAllContentSettingsRules(
       ContentSettingsType content_type) = 0;
 
   // Detaches the Provider from all Profile-related objects like PrefService.
   // This methods needs to be called before destroying the Profile.
   // Afterwards, none of the methods above that should only be called on the UI
   // thread should be called anymore.
-  virtual void ShutdownOnUIThread() {}
+  virtual void ShutdownOnUIThread() = 0;
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_