Clean up TestFeaturesNativeHandler to use the ExtensionsClient's JSON feature sources.

extensions/common/features/feature_provider.cc

Index: extensions/common/features/feature_provider.cc
diff --git a/extensions/common/features/feature_provider.cc b/extensions/common/features/feature_provider.cc
index b8f21f32db44984b248088fed4779d6c2701c1f4..1923836a91cf5dd71772bb22e68059d0c3e0af1c 100644
--- a/extensions/common/features/feature_provider.cc
+++ b/extensions/common/features/feature_provider.cc
@@ -47,22 +47,22 @@ base::LazyInstance<Static> g_static = LAZY_INSTANCE_INITIALIZER;
 }  // namespace
 
 // static
-FeatureProvider* FeatureProvider::GetByName(const std::string& name) {
+const FeatureProvider* FeatureProvider::GetByName(const std::string& name) {
   return g_static.Get().GetFeatures(name);
 }
 
 // static
-FeatureProvider* FeatureProvider::GetAPIFeatures() {
+const FeatureProvider* FeatureProvider::GetAPIFeatures() {
   return GetByName("api");
 }
 
 // static
-FeatureProvider* FeatureProvider::GetManifestFeatures() {
+const FeatureProvider* FeatureProvider::GetManifestFeatures() {
   return GetByName("manifest");
 }
 
 // static
-FeatureProvider* FeatureProvider::GetPermissionFeatures() {
+const FeatureProvider* FeatureProvider::GetPermissionFeatures() {
   return GetByName("permission");
 }