fix uninitialized variable warning for vs2012 compilation

net/http/http_response_headers.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.
 
 // The rules for header parsing were borrowed from Firefox:
 // http://lxr.mozilla.org/seamonkey/source/netwerk/protocol/http/src/nsHttpResponseHead.cpp
 // The rules for parsing content-types were also borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_response_headers.h"
@@ skipping 1277 matching lines @@
   dict->Set("headers", headers);
   return dict;
 }
 
 // static
 bool HttpResponseHeaders::FromNetLogParam(
     const base::Value* event_param,
     scoped_refptr<HttpResponseHeaders>* http_response_headers) {
   *http_response_headers = NULL;
 
-  const base::DictionaryValue* dict;
-  const base::ListValue* header_list;
+  const base::DictionaryValue* dict = NULL;
+  const base::ListValue* header_list = NULL;
 
   if (!event_param ||
       !event_param->GetAsDictionary(&dict) ||
       !dict->GetList("headers", &header_list)) {
     return false;
   }
 
   std::string raw_headers;
   for (base::ListValue::const_iterator it = header_list->begin();
        it != header_list->end();
@@ skipping 10 matching lines @@
   return true;
 }
 
 bool HttpResponseHeaders::IsChunkEncoded() const {
   // Ignore spurious chunked responses from HTTP/1.0 servers and proxies.
   return GetHttpVersion() >= HttpVersion(1, 1) &&
       HasHeaderValue("Transfer-Encoding", "chunked");
 }
 
 }  // namespace net