[Extensions Bindings] Add native declarativeContent verification

chrome/browser/extensions/api/declarative_content/content_constants.h

-// Copyright (c) 2012 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.
-
-// Constants used for the declarativeContent API.
-
-#ifndef CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_CONSTANTS_H_
-#define CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_CONSTANTS_H_
-
-namespace extensions {
-namespace declarative_content_constants {
-
-// Signals to which ContentRulesRegistries are registered.
-extern const char kOnPageChanged[];
-
-// Keys of dictionaries.
-extern const char kAllFrames[];
-extern const char kCss[];
-extern const char kInstanceType[];
-extern const char kIsBookmarked[];
-extern const char kJs[];
-extern const char kMatchAboutBlank[];
-extern const char kPageUrl[];
-
-// Values of dictionaries, in particular instance types
-extern const char kPageStateMatcherType[];
-extern const char kShowPageAction[];
-extern const char kRequestContentScript[];
-extern const char kSetIcon[];
-
-}  // namespace declarative_content_constants
-}  // namespace extensions
-
-#endif  // CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_CONSTANTS_H_