[Extensions] Add a SimpleFeature::Validate function

extensions/common/features/api_feature.h

Index: extensions/common/features/api_feature.h
diff --git a/extensions/common/features/api_feature.h b/extensions/common/features/api_feature.h
index 7a30cb432d0f07602358b11952c89e01c8f9c243..38247dc073166b26ee0bd5ee114303c01fee4e27 100644
--- a/extensions/common/features/api_feature.h
+++ b/extensions/common/features/api_feature.h
@@ -17,12 +17,7 @@ class APIFeature : public SimpleFeature {
   ~APIFeature() override;
 
   // extensions::Feature:
-  bool IsInternal() const override;
-
-  std::string Parse(const base::DictionaryValue* value) override;
-
- private:
-  bool internal_;
+  bool Validate(std::string* error) override;
 };
 
 }  // namespace extensions