Remove HTTP pipelining support.

net/base/net_error_list.h

 // 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.
 
 // This file intentionally does not have header guards, it's included
 // inside a macro to generate enum values.
 
 // This file contains the list of network errors.
 
 //
@@ skipping 552 matching lines @@
 // The HTTP response contained multiple Location headers.
 NET_ERROR(RESPONSE_HEADERS_MULTIPLE_LOCATION, -350)
 
 // SPDY server refused the stream. Client should retry. This should never be a
 // user-visible error.
 NET_ERROR(SPDY_SERVER_REFUSED_STREAM, -351)
 
 // SPDY server didn't respond to the PING message.
 NET_ERROR(SPDY_PING_FAILED, -352)
 
-// The request couldn't be completed on an HTTP pipeline. Client should retry.
-NET_ERROR(PIPELINE_EVICTION, -353)
+// Obsolete.  Kept here to avoid reuse, as the old error can still appear on
+// histograms.
+// NET_ERROR(PIPELINE_EVICTION, -353)
 
 // The HTTP response body transferred fewer bytes than were advertised by the
 // Content-Length header when the connection is closed.
 NET_ERROR(CONTENT_LENGTH_MISMATCH, -354)
 
 // The HTTP response body is transferred with Chunked-Encoding, but the
 // terminating zero-length chunk was never sent when the connection is closed.
 NET_ERROR(INCOMPLETE_CHUNKED_ENCODING, -355)
 
 // There is a QUIC protocol error.
@@ skipping 154 matching lines @@
 NET_ERROR(DNS_TIMED_OUT, -803)
 
 // The entry was not found in cache, for cache-only lookups.
 NET_ERROR(DNS_CACHE_MISS, -804)
 
 // Suffix search list rules prevent resolution of the given host name.
 NET_ERROR(DNS_SEARCH_EMPTY, -805)
 
 // Failed to sort addresses according to RFC3484.
 NET_ERROR(DNS_SORT_ERROR, -806)