Change MISSING_VIA_HEADER_4XX bypasses to only last 1 second.

components/data_reduction_proxy/common/data_reduction_proxy_headers.cc

 // Copyright 2014 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 "components/data_reduction_proxy/common/data_reduction_proxy_headers.h"
 
 #include <string>
 #include <vector>
 
 #include "base/rand_util.h"
@@ skipping 222 matching lines @@
       (headers->response_code() != net::HTTP_NOT_MODIFIED)) {
     // A Via header might not be present in a 304. Since the goal of a 304
     // response is to minimize information transfer, a sender in general
     // should not generate representation metadata other than Cache-Control,
     // Content-Location, Date, ETag, Expires, and Vary.
 
     // The proxy Via header might also not be present in a 4xx response.
     // Separate this case from other responses that are missing the header.
     if (headers->response_code() >= net::HTTP_BAD_REQUEST &&
         headers->response_code() < net::HTTP_INTERNAL_SERVER_ERROR) {
+      // At this point, any 4xx response that is missing the via header
+      // indicates an issue that is scoped to only the current request, so only
+      // bypass the data reduction proxy for a second.
+      // TODO(sclittle): Change this to only bypass the current request once
+      // that is fully supported, see http://crbug.com/418342.
+      data_reduction_proxy_info->bypass_duration = TimeDelta::FromSeconds(1);
       return BYPASS_EVENT_TYPE_MISSING_VIA_HEADER_4XX;
     }
     return BYPASS_EVENT_TYPE_MISSING_VIA_HEADER_OTHER;
   }
   // There is no bypass event.
   return BYPASS_EVENT_TYPE_MAX;
 }
 
 bool GetDataReductionProxyActionFingerprintChromeProxy(
     const net::HttpResponseHeaders* headers,
@@ skipping 47 matching lines @@
           value.begin() + chrome_proxy_fingerprint_prefix.size(),
           chrome_proxy_fingerprint_prefix.c_str())) {
         continue;
       }
     }
     values->push_back(value);
   }
 }
 
 }  // namespace data_reduction_proxy