Implemented declarative redirects to transparent image and empty document.

chrome/browser/extensions/api/declarative_webrequest/webrequest_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 WebRequest API.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_WEBREQUEST_WEBREQUEST_CONSTANTS_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_WEBREQUEST_WEBREQUEST_CONSTANTS_H_
 #pragma once
 
 namespace extensions {
 namespace declarative_webrequest_constants {
 
 // Signals to which WebRequestRulesRegistries are registered.
 extern const char kOnRequest[];
 
 // Keys of dictionaries.
 extern const char kInstanceTypeKey[];
 extern const char kRedirectUrlKey[];
 extern const char kResourceTypeKey[];
 extern const char kUrlKey[];
 
 // Values of dictionaries, in particular instance types
 extern const char kCancelRequestType[];
 extern const char kRedirectRequestType[];
+extern const char kRedirectToEmptyDocumentType[];
+extern const char kRedirectToTransparentImageType[];
 extern const char kRequestMatcherType[];
 
 }  // namespace declarative_webrequest_constants
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_WEBREQUEST_WEBREQUEST_CONSTANTS_H_