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

components/content_settings/core/browser/host_content_settings_map.cc

Index: components/content_settings/core/browser/host_content_settings_map.cc
diff --git a/components/content_settings/core/browser/host_content_settings_map.cc b/components/content_settings/core/browser/host_content_settings_map.cc
index e023a79de22361915f1499f27f64f05dca79beb0..945014840cd8f8893c2dcaf0a6b0ec938cf503f6 100644
--- a/components/content_settings/core/browser/host_content_settings_map.cc
+++ b/components/content_settings/core/browser/host_content_settings_map.cc
@@ -53,6 +53,7 @@ const ProviderNamesSourceMapEntry kProviderNamesSourceMap[] = {
     {"supervised_user", content_settings::SETTING_SOURCE_SUPERVISED},
     {"extension", content_settings::SETTING_SOURCE_EXTENSION},
     {"preference", content_settings::SETTING_SOURCE_USER},
+    {"recommended", content_settings::SETTING_SOURCE_RECOMMENDED_POLICY},
     {"default", content_settings::SETTING_SOURCE_USER},
 };
 
@@ -147,10 +148,24 @@ HostContentSettingsMap::HostContentSettingsMap(PrefService* prefs,
       prefs_(prefs),
       is_off_the_record_(is_incognito_profile || is_guest_profile) {
   DCHECK(!(is_incognito_profile && is_guest_profile));
-  content_settings::ObservableProvider* policy_provider =
-      new content_settings::PolicyProvider(prefs_);
-  policy_provider->AddObserver(this);
-  content_settings_providers_[POLICY_PROVIDER] = policy_provider;
+
+  // Mandatory policies.
+  content_settings::ObservableProvider* mandatory_policy_provider =
+      new content_settings::PolicyProvider(prefs_, false);
+  content_settings_providers_[POLICY_PROVIDER] = mandatory_policy_provider;
+
+  // Recommended policies.
+  content_settings::ObservableProvider* recommended_policy_provider =
+      new content_settings::PolicyProvider(prefs_, true);
+  content_settings_providers_[RECOMMENDED_POLICY_PROVIDER] =
+      recommended_policy_provider;
+
+  // FIXME(huangs): |policy_provider| and |recommended_policy_provider| both
+  // observe the same events, and sends trivial data to its observers. To
+  // prevent redundancy, we call AddObserver() for only one of them. Refactoring
+  // is needed for a cleaner solution.
+  mandatory_policy_provider->AddObserver(this);
+  recommended_policy_provider->AddObserver(this);
 
   content_settings::PrefProvider* pref_provider =
       new content_settings::PrefProvider(prefs_, is_off_the_record_);
@@ -221,6 +236,8 @@ ContentSetting HostContentSettingsMap::GetDefaultContentSetting(
     ContentSettingsType content_type,
     std::string* provider_id) const {
   UsedContentSettingsProviders();
+  ContentSetting recommended_default_setting = CONTENT_SETTING_DEFAULT;
+  ContentSetting default_default_setting = CONTENT_SETTING_DEFAULT;
 
   // Iterate through the list of providers and return the first non-NULL value
   // that matches |primary_url| and |secondary_url|.
@@ -239,13 +256,57 @@ ContentSetting HostContentSettingsMap::GetDefaultContentSetting(
               .get());
     }
     if (default_setting != CONTENT_SETTING_DEFAULT) {
-      if (provider_id)
-        *provider_id = kProviderNamesSourceMap[provider->first].provider_name;
-      return default_setting;
+      if (provider->first == RECOMMENDED_POLICY_PROVIDER) {
+        recommended_default_setting = default_setting;
+      } else if (provider->first == DEFAULT_PROVIDER) {
+        default_default_setting = default_setting;
+      } else {
+        if (provider_id)
+          *provider_id = kProviderNamesSourceMap[provider->first].provider_name;
+        return default_setting;
+      }
     }
   }
 
-  return CONTENT_SETTING_DEFAULT;
+  // Eearly exit if we found nothing.
+  if (recommended_default_setting == CONTENT_SETTING_DEFAULT &&
+      default_default_setting == CONTENT_SETTING_DEFAULT) {
+    return CONTENT_SETTING_DEFAULT;
+  }
+
+  // Recommended policy provider subsumes default provider.
+  if (default_default_setting == CONTENT_SETTING_DEFAULT ||
+      default_default_setting == recommended_default_setting) {
+    if (provider_id) {
+      *provider_id =
+          kProviderNamesSourceMap[RECOMMENDED_POLICY_PROVIDER].provider_name;
+    }
+    return recommended_default_setting;
+  }
+
+  // Default provider.
+  if (provider_id)
+    *provider_id = kProviderNamesSourceMap[DEFAULT_PROVIDER].provider_name;
+  return default_default_setting;
+}
+
+ContentSetting HostContentSettingsMap::GetRecommendedDefaultContentSetting(
+    ContentSettingsType content_type) const {
+  ConstProviderIterator provider = content_settings_providers_.find(
+      RECOMMENDED_POLICY_PROVIDER);
+  if (provider == content_settings_providers_.end())
+    return CONTENT_SETTING_DEFAULT;
+
+  ContentSetting default_setting =
+      GetDefaultContentSettingFromProvider(content_type, provider->second);
+  if (is_off_the_record_) {
+    default_setting = content_settings::ValueToContentSetting(
+        ProcessIncognitoInheritanceBehavior(
+            content_type,
+            content_settings::ContentSettingToValue(default_setting))
+            .get());
+  }
+  return default_setting;
 }
 
 ContentSetting HostContentSettingsMap::GetContentSetting(