Add a policy to re-enable deprecated web platform features.

chrome/browser/policy/configuration_policy_handler_list_factory.cc

Index: chrome/browser/policy/configuration_policy_handler_list_factory.cc
diff --git a/chrome/browser/policy/configuration_policy_handler_list_factory.cc b/chrome/browser/policy/configuration_policy_handler_list_factory.cc
index 849ea2c012eea3ca0ca98c86646f92df7470d559..74bd8e651c08dbb09af6d67f230c483627eaa96e 100644
--- a/chrome/browser/policy/configuration_policy_handler_list_factory.cc
+++ b/chrome/browser/policy/configuration_policy_handler_list_factory.cc
@@ -25,6 +25,7 @@
 #include "components/translate/core/common/translate_pref_names.h"
 #include "grit/component_strings.h"
 #include "policy/policy_constants.h"
+#include "webkit/common/webpreferences.h"
 
 #if !defined(OS_IOS)
 #include "chrome/browser/extensions/api/messaging/native_messaging_policy_handler.h"
@@ -491,6 +492,14 @@ StringToIntEnumListPolicyHandler::MappingEntry kExtensionAllowedTypesMap[] = {
   { "legacy_packaged_app", extensions::Manifest::TYPE_LEGACY_PACKAGED_APP },
   { "platform_app", extensions::Manifest::TYPE_PLATFORM_APP },
 };
+
+// Maps feature tags as specified in policy to the corresponding enum value.
+StringToIntEnumListPolicyHandler::MappingEntry
+    kEnableDeprecatedWebPlatformFeaturesMap[] = {
+  // TODO: Remove after 2015-04-30 per http://crbug.com/374782.
+  { "ShowModalDialog_EffectiveUntil20150430",
+    webkit_glue::DEPRECATED_FEATURE_SHOW_MODAL_DIALOG },
+};
 #endif  // !defined(OS_IOS)
 
 }  // namespace
@@ -561,6 +570,13 @@ scoped_ptr<ConfigurationPolicyHandlerList> BuildHandlerList(
           extensions::pref_names::kAllowedTypes,
           kExtensionAllowedTypesMap,
           kExtensionAllowedTypesMap + arraysize(kExtensionAllowedTypesMap))));
+  handlers->AddHandler(make_scoped_ptr<ConfigurationPolicyHandler>(
+      new StringToIntEnumListPolicyHandler(
+          key::kEnableDeprecatedWebPlatformFeatures,
+          prefs::kWebKitEnableDeprecatedFeatures,
+          kEnableDeprecatedWebPlatformFeaturesMap,
+          kEnableDeprecatedWebPlatformFeaturesMap +
+              arraysize(kEnableDeprecatedWebPlatformFeaturesMap))));
 #endif  // !defined(OS_IOS)
 
 #if !defined(OS_CHROMEOS) && !defined(OS_ANDROID) && !defined(OS_IOS)