DCHECK that hostname is not empty in MarkAlternativeServiceBroken.

net/http/http_server_properties_impl.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_server_properties_impl.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 297 matching lines @@
     if (base::EndsWith(origin.host(), canonical_suffixes_[i], false)) {
       HostPortPair canonical_host(canonical_suffix, origin.port());
       canonical_host_to_origin_map_[canonical_host] = origin;
       break;
     }
   }
 }
 
 void HttpServerPropertiesImpl::MarkAlternativeServiceBroken(
     const AlternativeService& alternative_service) {
+  // Empty host means use host of origin, callers are supposed to substitute.
+  DCHECK(!alternative_service.host.empty());
   if (alternative_service.protocol == UNINITIALIZED_ALTERNATE_PROTOCOL) {
     LOG(DFATAL) << "Trying to mark unknown alternate protocol broken.";
     return;
   }
   int count = ++recently_broken_alternative_services_[alternative_service];
   base::TimeDelta delay =
       base::TimeDelta::FromSeconds(kBrokenAlternativeProtocolDelaySecs);
   base::TimeTicks when = base::TimeTicks::Now() + delay * (1 << (count - 1));
   auto result = broken_alternative_services_.insert(
       std::make_pair(alternative_service, when));
@@ skipping 254 matching lines @@
   base::TimeDelta delay = when > now ? when - now : base::TimeDelta();
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE,
       base::Bind(
           &HttpServerPropertiesImpl::ExpireBrokenAlternateProtocolMappings,
           weak_ptr_factory_.GetWeakPtr()),
       delay);
 }
 
 }  // namespace net