Implement API features for the Extension API feature system

chrome/common/extensions/features/permission_feature.cc

Index: chrome/common/extensions/features/permission_feature.cc
diff --git a/chrome/common/extensions/features/permission_feature.cc b/chrome/common/extensions/features/permission_feature.cc
index 1f5da626995751a25540285db3da55a47a772af0..72b261f5ad73fb61a8e9fcbadebb47b3a4d4a6dc 100644
--- a/chrome/common/extensions/features/permission_feature.cc
+++ b/chrome/common/extensions/features/permission_feature.cc
@@ -36,4 +36,20 @@ Feature::Availability PermissionFeature::IsAvailableToContext(
   return CreateAvailability(IS_AVAILABLE);
 }
 
+std::string PermissionFeature::Parse(const DictionaryValue* value) {
+  std::string error = SimpleFeature::Parse(value);
+  if (!error.empty())
+    return error;
+
+  if (extension_types()->empty()) {
+    return name() + ": Permission features must specify at least one " +
+        "value for extension_types.";
+  }
+
+  if (!GetContexts()->empty())
+    return name() + ": Permission features do not support contexts.";
+
+  return "";
+}
+
 }  // namespace