[Extensions Bindings] Add enum support

extensions/renderer/argument_spec.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_RENDERER_ARGUMENT_SPEC_H_
 #define EXTENSIONS_RENDERER_ARGUMENT_SPEC_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 42 matching lines @@
   // |out_value|. Otherwise, no conversion is performed.
   bool ParseArgument(v8::Local<v8::Context> context,
                      v8::Local<v8::Value> value,
                      const RefMap& refs,
                      std::unique_ptr<base::Value>* out_value,
                      std::string* error) const;
 
   const std::string& name() const { return name_; }
   bool optional() const { return optional_; }
   ArgumentType type() const { return type_; }
+  const std::set<std::string>& enum_values() const { return enum_values_; }
 
  private:
   // Initializes this object according to |type_string| and |dict|.
   void InitializeType(const base::DictionaryValue* dict);
 
   // Returns true if this argument refers to a fundamental type.
   bool IsFundamentalType() const;
 
   // Conversion functions. These should only be used if the spec is of the given
   // type (otherwise, they will DCHECK).
@@ skipping 45 matching lines @@
 
   // The possible enum values, if defined for this argument.
   std::set<std::string> enum_values_;
 
   DISALLOW_COPY_AND_ASSIGN(ArgumentSpec);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_ARGUMENT_SPEC_H_