CHECK for that we are not seeing user-visible SPDY_PING_FAILED errors.

net/http/http_network_transaction.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_network_transaction.h"
 
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 146 matching lines @@
 
   if (request_->load_flags & LOAD_DISABLE_CERT_REVOCATION_CHECKING) {
     server_ssl_config_.rev_checking_enabled = false;
     proxy_ssl_config_.rev_checking_enabled = false;
   }
 
   next_state_ = STATE_CREATE_STREAM;
   int rv = DoLoop(OK);
   if (rv == ERR_IO_PENDING)
     callback_ = callback;
+  CHECK_NE(rv, ERR_SPDY_PING_FAILED);
   return rv;
 }
 
 int HttpNetworkTransaction::RestartIgnoringLastError(
     const CompletionCallback& callback) {
   DCHECK(!stream_.get());
   DCHECK(!stream_request_.get());
   DCHECK_EQ(STATE_NONE, next_state_);
 
   next_state_ = STATE_CREATE_STREAM;
@@ skipping 286 matching lines @@
   stream_.reset(stream);
   stream_request_.reset();  // we're done with the stream request
   OnIOComplete(ERR_HTTPS_PROXY_TUNNEL_RESPONSE);
 }
 
 bool HttpNetworkTransaction::is_https_request() const {
   return request_->url.SchemeIs("https");
 }
 
 void HttpNetworkTransaction::DoCallback(int rv) {
+  CHECK_NE(rv, ERR_SPDY_PING_FAILED);
   DCHECK_NE(rv, ERR_IO_PENDING);
   DCHECK(!callback_.is_null());
 
   // Since Run may result in Read being called, clear user_callback_ up front.
   CompletionCallback c = callback_;
   callback_.Reset();
   c.Run(rv);
 }
 
 void HttpNetworkTransaction::OnIOComplete(int result) {
@@ skipping 890 matching lines @@
       description = base::StringPrintf("Unknown state 0x%08X (%u)", state,
                                        state);
       break;
   }
   return description;
 }
 
 #undef STATE_CASE
 
 }  // namespace net