Make ExtensionContentSettingsStore refcounted.

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 63 matching lines @@
       const GURL& primary_url,
       const GURL& secondary_url,
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier) const = 0;
 
   // Sets the content setting for a particular |primary_pattern|,
   // |secondary_pattern|, |content_type| tuple. For ContentSettingsTypes that
   // require a resource identifier to be specified, the |resource_identifier|
   // must be non-empty.
   //
-  // This should only be called on the UI thread.
+  // This should only be called on the UI thread, and not after
+  // ShutdownOnUIThread has been called.

[battre, 2011/07/06 09:12:05]

Just a thought:

should we codify this contract? I.e. do something like

void SetContentSetting(...) {
  DCHECK(not_shut_down);
  SetContentSettingImpl(...);
}
protected:
virtual void SetContentSettingImpl(...) = 0;

[Bernhard Bauer, 2011/07/06 12:06:51]

http://codereview.chromium.org/7218073 adds a DCHECK like that in
content_settings::PrefProvider (which has the only non-empty implementation).

   virtual void SetContentSetting(
       const ContentSettingsPattern& primary_pattern,
       const ContentSettingsPattern& secondary_pattern,
       ContentSettingsType content_type,
       const ResourceIdentifier& resource_identifier,
       ContentSetting content_setting) = 0;
 
   // For a given content type, returns all content setting rules with a
   // non-default setting, mapped to their actual settings.
   // |content_settings_rules| must be non-NULL. If this provider was created for
   // the incognito profile, it will only return those settings differing
   // from the corresponding regular provider. For ContentSettingsTypes that
   // require a resource identifier to be specified, the |resource_identifier|
   // 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
   // |content_type| will be reset to CONTENT_SETTING_DEFAULT.
   //
-  // This should only be called on the UI thread.
+  // This should only be called on the UI thread  , and not after

[battre, 2011/07/06 09:12:05]

nit: space

[Bernhard Bauer, 2011/07/06 12:06:51]

Done.

+  // ShutdownOnUIThread has been called.
   virtual void ClearAllContentSettingsRules(
       ContentSettingsType content_type) = 0;
 
   // Resets all content settings to CONTENT_SETTINGS_DEFAULT.
   //
-  // This should only be called on the UI thread.
+  // This should only be called on the UI thread, and not after
+  // ShutdownOnUIThread has been called.
   virtual void ResetToDefaults() = 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() {}
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_