Delegating the "are images allowed" decision to renderer.

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 32 matching lines @@
   // 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 {
+    typedef bool (*SortFunction)(
+        const ProviderInterface::Rule&,
+        const ProviderInterface::Rule&);
     Rule();
     Rule(const ContentSettingsPattern& primary_pattern,
          const ContentSettingsPattern& secondary_pattern,
          ContentSetting setting);
 
     ContentSettingsPattern primary_pattern;
     ContentSettingsPattern secondary_pattern;
     ContentSetting content_setting;
+
+    static bool LexicographicalSort(
+        const ProviderInterface::Rule& a,
+        const ProviderInterface::Rule& b);
+
+    static bool PatternPrecedenceSort(
+        const ProviderInterface::Rule& a,
+        const ProviderInterface::Rule& b);
   };
 
   typedef std::vector<Rule> Rules;
 
   virtual ~ProviderInterface() {}
 
   // Returns a single ContentSetting which applies to a given |primary_url|,
   // |secondary_url| pair or CONTENT_SETTING_DEFAULT, if no rule applies. For
   // ContentSettingsTypes that require a resource identifier to be specified,
   // the |resource_identifier| must be non-empty.
@@ skipping 61 matching lines @@
   // 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() = 0;
 };
 
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_PROVIDER_H_