Delegating the "are images allowed" decision to renderer.

chrome/browser/content_settings/content_settings_provider.cc

 // 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.
 
 #include "chrome/browser/content_settings/content_settings_provider.h"
 
 namespace content_settings {
 
 ProviderInterface::Rule::Rule()
     : content_setting(CONTENT_SETTING_DEFAULT) {
 }
 
 ProviderInterface::Rule::Rule(const ContentSettingsPattern& primary_pattern,
                               const ContentSettingsPattern& secondary_pattern,
                               ContentSetting setting)
     : primary_pattern(primary_pattern),
       secondary_pattern(secondary_pattern),
       content_setting(setting) {
 }
 
+bool ProviderInterface::Rule::operator<(const Rule& rhs) const {
+  if (primary_pattern < rhs.primary_pattern)
+    return true;
+  if (rhs.primary_pattern < primary_pattern)
+    return false;
+  return (secondary_pattern < rhs.secondary_pattern);
+}
+
 }  // namespace content_settings