Improve merging of header modifications in webRequest.OnHeadersReceived

chrome/browser/extensions/extension_webrequest_api_helpers.h

 // Copyright (c) 2011 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_EXTENSION_WEBREQUEST_API_HELPERS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBREQUEST_API_HELPERS_H_
 #pragma once
 
@@ skipping 11 matching lines @@
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 
 namespace base {
 class ListValue;
 class Value;
 }
 
 namespace extension_webrequest_api_helpers {
 
+typedef std::pair<std::string, std::string> ResponseHeader;
+typedef std::vector<ResponseHeader> ResponseHeaders;
+
 // Contains the modification an extension wants to perform on an event.
 struct EventResponseDelta {
   // ID of the extension that sent this response.
   std::string extension_id;
 
   // The time that the extension was installed. Used for deciding order of
   // precedence in case multiple extensions respond with conflicting
   // decisions.
   base::Time extension_install_time;
 
   // Response values. These are mutually exclusive.
   bool cancel;
   GURL new_url;
 
   // Newly introduced or overridden request headers.
   net::HttpRequestHeaders modified_request_headers;
 
   // Keys of request headers to be deleted.
   std::vector<std::string> deleted_request_headers;
 
-  // Complete set of response headers that will replace the original ones.
-  scoped_refptr<net::HttpResponseHeaders> new_response_headers;
+  // Headers that were added to the response. A modification of a header
+  // corresponds to a deletion and subsequent addition of the new header.
+  ResponseHeaders added_response_headers;
+
+  // Headers that were deleted from the response.
+  ResponseHeaders deleted_response_headers;
 
   // Authentication Credentials to use.
   scoped_ptr<net::AuthCredentials> auth_credentials;
 
   EventResponseDelta(const std::string& extension_id,
                      const base::Time& extension_install_time);
   ~EventResponseDelta();
 
   DISALLOW_COPY_AND_ASSIGN(EventResponseDelta);
 };
@@ skipping 39 matching lines @@
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
     const GURL& new_url);
 EventResponseDelta* CalculateOnBeforeSendHeadersDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
     net::HttpRequestHeaders* old_headers,
     net::HttpRequestHeaders* new_headers);
-// |status_line| contains the status line of the original request. Together
-// with |response_headers_string| we can assemble a complete new response
-// header. |response_headers_string| contains all headers with \n as line
-// separator. It terminates with two \n.
 EventResponseDelta* CalculateOnHeadersReceivedDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
-    const std::string& status_line,
-    const std::string& response_headers_string);
+    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.
 // The |deltas| need to be sorted in decreasing order of precedence of
@@ skipping 14 matching lines @@
     GURL* new_url,
     std::set<std::string>* conflicting_extensions,
     EventLogEntries* event_log_entries);
 // Modifies the headers in |request_headers| according to |deltas|. Conflicts
 // are tried to be resolved.
 void MergeOnBeforeSendHeadersResponses(
     const EventResponseDeltas& deltas,
     net::HttpRequestHeaders* request_headers,
     std::set<std::string>* conflicting_extensions,
     EventLogEntries* event_log_entries);
-// Overrides |override_response_headers| with the response headers returned
-// by the extension with the highest precedence.
-// TODO(battre) Implement merging of response header modifications.
+// Stores a copy of |original_response_header| into |override_response_headers|
+// that is modified according to |deltas|. If |deltas| does not instruct to
+// modify the response headers, |override_response_headers| remains empty.
 void MergeOnHeadersReceivedResponses(
     const EventResponseDeltas& deltas,
+    const net::HttpResponseHeaders* original_response_headers,
     scoped_refptr<net::HttpResponseHeaders>* override_response_headers,
     std::set<std::string>* conflicting_extensions,
     EventLogEntries* event_log_entries);
 // Merge the responses of blocked onAuthRequired handlers. The first
 // registered listener that supplies authentication credentials in a response,
 // if any, will have its authentication credentials used. |request| must be
 // non-NULL, and contain |deltas| that are sorted in decreasing order of
 // precedence.
 // Returns whether authentication credentials are set.
 bool MergeOnAuthRequiredResponses(
     const EventResponseDeltas& deltas,
     net::AuthCredentials* auth_credentials,
     std::set<std::string>* conflicting_extensions,
     EventLogEntries* event_log_entries);
 
 }  // namespace extension_webrequest_api_helpers
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_WEBREQUEST_API_HELPERS_H_