CHECK to make sure connection_group is never empty.

net/http/http_network_transaction.cc

 // Copyright (c) 2006-2009 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 "base/scoped_ptr.h"
 #include "base/compiler_specific.h"
 #include "base/field_trial.h"
 #include "base/string_util.h"
@@ skipping 574 matching lines @@
     port = request_->url.EffectiveIntPort();
   }
 
   // For a connection via HTTP proxy not using CONNECT, the connection
   // is to the proxy server only. For all other cases
   // (direct, HTTP proxy CONNECT, SOCKS), the connection is upto the
   // url endpoint. Hence we append the url data into the connection_group.
   if (proxy_mode_ != kHTTPProxy)
     connection_group.append(request_->url.GetOrigin().spec());
 
-  DCHECK(!connection_group.empty());
+  // TODO(willchan): Downgrade this back to a DCHECK after closing
+  // http://crbug.com/15374.
+  CHECK(!connection_group.empty()) << "URL: " << request_->url.GetOrigin()
+                                   << ", Host: " << host
+                                   << ", Port: " << port;
 
   HostResolver::RequestInfo resolve_info(host, port);
 
   // The referrer is used by the DNS prefetch system to corellate resolutions
   // with the page that triggered them. It doesn't impact the actual addresses
   // that we resolve to.
   resolve_info.set_referrer(request_->referrer);
 
   // If the user is refreshing the page, bypass the host cache.
   if (request_->load_flags & LOAD_BYPASS_CACHE ||
@@ skipping 1159 matching lines @@
     host_and_port = proxy_info_.proxy_server().host_and_port();
   } else {
     DCHECK(target == HttpAuth::AUTH_SERVER);
     host_and_port = GetHostAndPort(request_->url);
   }
   auth_info->host_and_port = ASCIIToWide(host_and_port);
   response_.auth_challenge = auth_info;
 }
 
 }  // namespace net