[Extensions] Add extension feature generation code

tools/json_schema_compiler/test/BUILD.gn

Index: tools/json_schema_compiler/test/BUILD.gn
diff --git a/tools/json_schema_compiler/test/BUILD.gn b/tools/json_schema_compiler/test/BUILD.gn
index 22a23af979ad9c3063e5b3274976e4c8c8e49245..ea465f5b457496afa8478892e50af009f61850c3 100644
--- a/tools/json_schema_compiler/test/BUILD.gn
+++ b/tools/json_schema_compiler/test/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/json_schema_api.gni")
+import("//build/json_features.gni")
 
 json_schema_api("api") {
   visibility = [ ":*" ]
@@ -32,6 +33,15 @@ json_schema_api("api") {
   root_namespace = "test::api::%(namespace)s"
 }
 
+json_features("features_test") {
+  feature_class = "APIFeature"
+  provider_class = "TestAPIFeatureProvider"
+  sources = [
+    "features_test.json",
+    "features_test2.json",
+  ]
+}
+
 source_set("test") {
   testonly = true
   sources = [
@@ -44,6 +54,7 @@ source_set("test") {
 
   public_deps = [
     ":api",
+    ":features_test",
     "//base",
   ]
 }