[Extensions Bindings] Add argument parsing errors

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 95 matching lines @@
   bool ParseArgumentToArray(v8::Local<v8::Context> context,
                             v8::Local<v8::Array> value,
                             const APITypeReferenceMap& refs,
                             std::unique_ptr<base::Value>* out_value,
                             std::string* error) const;
   bool ParseArgumentToAny(v8::Local<v8::Context> context,
                           v8::Local<v8::Value> value,
                           std::unique_ptr<base::Value>* out_value,
                           std::string* error) const;
 
+  // Returns an error message indicating the type of |value| does not match the
+  // expected type.
+  std::string GetInvalidTypeError(v8::Local<v8::Value> value) const;
+
   // The name of the argument.
   std::string name_;
 
   // The type of the argument.
   ArgumentType type_;
 
   // Whether or not the argument is required.
   bool optional_;
 
   // The reference the argument points to, if any. Note that if this is set,
@@ skipping 33 matching lines @@
   // to allow the API to pass an object with arbitrary properties. Only
   // applicable for ArgumentType::OBJECT.
   std::unique_ptr<ArgumentSpec> additional_properties_;
 
   DISALLOW_COPY_AND_ASSIGN(ArgumentSpec);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_ARGUMENT_SPEC_H_