[Policy Experimental] Add "recommended" policies for URL exceptions.

components/content_settings/core/browser/host_content_settings_map.h

Index: components/content_settings/core/browser/host_content_settings_map.h
diff --git a/components/content_settings/core/browser/host_content_settings_map.h b/components/content_settings/core/browser/host_content_settings_map.h
index 927305765c5d708efa37b1f53d6afcfbffb2260c..9c3bbdcc7eaa2d4552272b0fc71b57749ff40004 100644
--- a/components/content_settings/core/browser/host_content_settings_map.h
+++ b/components/content_settings/core/browser/host_content_settings_map.h
@@ -57,6 +57,7 @@ class HostContentSettingsMap : public content_settings::Observer,
     SUPERVISED_PROVIDER,
     CUSTOM_EXTENSION_PROVIDER,
     PREF_PROVIDER,
+    RECOMMENDED_POLICY_PROVIDER,
     DEFAULT_PROVIDER,
     NUM_PROVIDER_TYPES,
   };
@@ -83,6 +84,12 @@ class HostContentSettingsMap : public content_settings::Observer,
   ContentSetting GetDefaultContentSetting(ContentSettingsType content_type,
                                           std::string* provider_id) const;
 
+  // Returns the recommended setting for a particular content type.
+  //
+  // This may be called on any thread.
+  ContentSetting GetRecommendedDefaultContentSetting(
+      ContentSettingsType content_type) const;
+
   // Returns a single |ContentSetting| which applies to the given URLs.  Note
   // that certain internal schemes are whitelisted. For |CONTENT_TYPE_COOKIES|,
   // |CookieSettings| should be used instead. For content types that can't be