Fix a crash in HttpVaryData::MatchesRequests.

net/http/http_vary_data.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 "net/http/http_vary_data.h"
 
 #include <stdlib.h>
 
 #include "base/pickle.h"
 #include "base/strings/string_util.h"
@@ skipping 50 matching lines @@
 void HttpVaryData::Persist(base::Pickle* pickle) const {
   DCHECK(is_valid());
   pickle->WriteBytes(&request_digest_, sizeof(request_digest_));
 }
 
 bool HttpVaryData::MatchesRequest(
     const HttpRequestInfo& request_info,
     const HttpResponseHeaders& cached_response_headers) const {
   HttpVaryData new_vary_data;
   if (!new_vary_data.Init(request_info, cached_response_headers)) {
-    // This shouldn't happen provided the same response headers passed here
-    // were also used when initializing |this|.
-    NOTREACHED();
+    // This case can happen if |this| was loaded from a cache that was populated
+    // by a build before crbug.com/469675 was fixed.
     return false;
   }
   return memcmp(&new_vary_data.request_digest_, &request_digest_,
                 sizeof(request_digest_)) == 0;
 }
 
 // static
 std::string HttpVaryData::GetRequestValue(
     const HttpRequestInfo& request_info,
     const std::string& request_header) {
@@ skipping 17 matching lines @@
   // Append a character that cannot appear in the request header line so that we
   // protect against case where the concatenation of two request headers could
   // look the same for a variety of values for the individual request headers.
   // For example, "foo: 12\nbar: 3" looks like "foo: 1\nbar: 23" otherwise.
   request_value.append(1, '\n');
 
   base::MD5Update(ctx, request_value);
 }
 
 }  // namespace net