Use EnumerateHeaderLines to parse added headers in webRequest API

extensions/browser/api/web_request/web_request_api_helpers.cc

 // 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.
 
 #include "extensions/browser/api/web_request/web_request_api_helpers.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/bind.h"
@@ skipping 343 matching lines @@
           break;
         }
       }
       if (!header_found)
         result->deleted_response_headers.push_back(ResponseHeader(name, value));
     }
   }
 
   // Find added headers (header keys are treated case insensitively).
   {
-    for (ResponseHeaders::const_iterator i = new_response_headers->begin();
-         i != new_response_headers->end(); ++i) {
-      void* iter = NULL;
+    for (const auto& i : *new_response_headers) {
+      std::string name_lowercase = base::ToLowerASCII(i.first);
+      void* iter = nullptr;

[not at google - send to devlin, 2015/09/08 22:55:34]

I presume you don't need |iter| for anything?

[robwu, 2015/09/08 23:00:21]

iter is just used to keep track of the header iterator state.

+      std::string name;
       std::string value;
       bool header_found = false;
-      while (old_response_headers->EnumerateHeader(&iter, i->first, &value) &&
-             !header_found) {
-        header_found = (value == i->second);
+      while (old_response_headers->EnumerateHeaderLines(&iter, &name, &value)) {
+        if (base::LowerCaseEqualsASCII(name, name_lowercase) &&

[not at google - send to devlin, 2015/09/08 22:55:34]

Seems like you could use EqualsCaseInsensitiveASCII and not need to lowercase
|i.first|?

[robwu, 2015/09/08 23:00:20]

Possibly, but transforming once to lowercase and storing the result in a
variable seems better than turning the characters to lowercase multiple times
for each header line.

+            value == i.second) {
+          header_found = true;
+          break;
+        }
       }
       if (!header_found)
-        result->added_response_headers.push_back(*i);
+        result->added_response_headers.push_back(i);
     }
   }
 
   return result;
 }
 
 EventResponseDelta* CalculateOnAuthRequiredDelta(
     const std::string& extension_id,
     const base::Time& extension_install_time,
     bool cancel,
@@ skipping 887 matching lines @@
       std::find(kResourceTypeStrings,
                 kResourceTypeStrings + kResourceTypeStringsLength,
                 type_str);
   if (iter == (kResourceTypeStrings + kResourceTypeStringsLength))
     return false;
   *type = kResourceTypeValues[iter - kResourceTypeStrings];
   return true;
 }
 
 }  // namespace extension_web_request_api_helpers