[Extensions Bindings] Add argument parsing errors

extensions/renderer/api_invocation_errors.h

+// Copyright 2017 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_API_INVOCATION_ERRORS_H_
+#define EXTENSIONS_RENDERER_API_INVOCATION_ERRORS_H_
+
+#include <set>
+#include <string>
+
+#include "base/strings/string_piece.h"
+
+// A collection of error-related strings and utilities for parsing API
+// invocations.
+namespace extensions {
+namespace api_errors {
+
+// Strings for the expected types.
+extern const char kTypeString[];
+extern const char kTypeDouble[];
+extern const char kTypeBoolean[];
+extern const char kTypeInteger[];
+extern const char kTypeObject[];
+extern const char kTypeList[];
+extern const char kTypeBinary[];
+extern const char kTypeFunction[];
+extern const char kTypeUndefined[];
+extern const char kTypeNull[];
+
+// Methods to return a formatted string describing an error related to argument
+// parsing.
+std::string InvalidEnumValue(const std::set<std::string>& valid_enums);
+std::string MissingRequiredProperty(const char* property_name);
+std::string UnexpectedProperty(const char* property_name);
+std::string TooFewArrayItems(int minimum);

[jbroman, 2017/04/26 14:34:26]

nit: You could also say how many were present (for this and string chars). Not a
big deal.

[Devlin, 2017/04/26 16:18:26]

Why not.  Done.

+std::string TooManyArrayItems(int maximum);
+std::string TooFewStringChars(int minimum);
+std::string TooManyStringChars(int maximum);
+std::string NumberTooSmall(int minimum);
+std::string NumberTooLarge(int maximum);
+std::string InvalidType(const char* expected_type, const char* actual_type);
+std::string NotAnInstance(const char* instance_type);
+std::string InvalidChoice();
+std::string UnserializableValue();
+std::string ScriptThrewError();
+
+// Returns an message indicating an error was found while parsing a given index
+// in an array.
+std::string IndexError(uint32_t index, const std::string& error);
+
+// Returns a message indicating that an error was found while parsing a given
+// property on an object.
+std::string PropertyError(const char* property_name, const std::string& error);
+
+}  // namespace api_errors
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_API_INVOCATION_ERRORS_H_