Introduce a content settings provider interface.

chrome/browser/content_settings/content_settings_provider.h

+// Copyright (c) 2010 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
+
+#include "chrome/common/content_settings.h"
+
+class ContentSettingsProviderInterface {
+ public:
+  // True if this provider can provide a default setting for the |content_type|.
+  virtual bool canProvideDefaultSetting(ContentSettingsType content_type) = 0;

[gfeher, 2010/11/30 12:20:59]

I think the style guide asks for capital letters at the beginning of method
names. Is this an exceptional case?

[jochen (gone - plz use gerrit), 2010/11/30 12:29:10]

Done.

+
+  // Returns the default content setting this provider has for the given
+  // |content_type|, or CONTENT_SETTING_DEFAULT if nothing be provided for this
+  // type.
+  virtual ContentSetting provideDefaultSetting(
+      ContentSettingsType content_type) = 0;
+
+  // 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) = 0;
+
+ protected:
+  virtual ~ContentSettingsProviderInterface() {};
+};
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_