Add an about:flag to support alternative data saver features

components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h

 // Copyright 2014 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 COMPONENTS_DATA_REDUCTION_PROXY_CORE_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_
 #define COMPONENTS_DATA_REDUCTION_PROXY_CORE_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 80 matching lines @@
 const char* compressed_video_directive();
 
 // Gets the directive used by the data reduction proxy to request that
 // a resource not be transformed.
 const char* identity_directive();
 
 // Gets the Chrome-Proxy directive used by data reduction proxy lite page
 // preview requests and responses.
 const char* chrome_proxy_lite_page_directive();
 
-// Gets the Chrome-Proxy directive used by data reduction proxy lite page
-// preview experiment to ignore the blacklist.
-const char* chrome_proxy_lite_page_ignore_blacklist_directive();
+// Gets the Chrome-Proxy "exp" directive value used by data reduction proxy lite
+// page preview experiment to ignore the blacklist.
+const char* chrome_proxy_lite_page_ignore_blacklist();
 
 // Requests a transformation only if the server determines that the page is
 // otherwise heavy (i.e., the associated page load ordinarily requires the
 // network to transfer of a lot of bytes). Added to a previews directive. E.g.,
 // "lite-page;if-heavy".
 const char* if_heavy_qualifier();
 
 // Returns true if the Chrome-Proxy-Content-Transform response header indicates
 // that an empty image has been provided.
 bool IsEmptyImagePreview(const net::HttpResponseHeaders& headers);
@@ skipping 66 matching lines @@
     const net::HttpResponseHeaders* headers,
     std::string* content_length_fingerprint);
 
 // Returns values of the Chrome-Proxy header, but with its fingerprint removed.
 void GetDataReductionProxyHeaderWithFingerprintRemoved(
     const net::HttpResponseHeaders* headers,
     std::vector<std::string>* values);
 
 }  // namespace data_reduction_proxy
 #endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_