Make original_response_headers parameter of NetworkDelegate::OnHeadersReceived const

chrome/browser/extensions/api/web_request/web_request_api_helpers.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.
 
 // Helper classes and functions used for the WebRequest API.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_
 #define CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_
 
 #include <list>
@@ skipping 178 matching lines @@
 EventResponseDelta* CalculateOnBeforeSendHeadersDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
     net::HttpRequestHeaders* old_headers,
     net::HttpRequestHeaders* new_headers);
 EventResponseDelta* CalculateOnHeadersReceivedDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
-    net::HttpResponseHeaders* old_response_headers,
+    const net::HttpResponseHeaders* old_response_headers,
     ResponseHeaders* new_response_headers);
 // Destructively moves the auth credentials from |auth_credentials| to the
 // returned EventResponseDelta.
 EventResponseDelta* CalculateOnAuthRequiredDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
     scoped_ptr<net::AuthCredentials>* auth_credentials);
 
 // These functions merge the responses (the |deltas|) of request handlers.
@@ skipping 74 matching lines @@
 // success.
 bool ParseResourceType(const std::string& type_str,
                        ResourceType::Type* type);
 
 // Triggers clearing each renderer's in-memory cache the next time it navigates.
 void ClearCacheOnNavigation();
 
 }  // namespace extension_web_request_api_helpers
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEB_REQUEST_WEB_REQUEST_API_HELPERS_H_