Add unit-tests for SingleRequestHostResolver.

net/base/single_request_host_resolver.cc

Index: net/base/single_request_host_resolver.cc
===================================================================
--- net/base/single_request_host_resolver.cc	(revision 87863)
+++ net/base/single_request_host_resolver.cc	(working copy)
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "net/base/host_resolver.h"
+#include "net/base/single_request_host_resolver.h"
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ -10,30 +10,6 @@
 
 namespace net {
 
-HostResolver::RequestInfo::RequestInfo(const HostPortPair& host_port_pair)
-    : host_port_pair_(host_port_pair),
-      address_family_(ADDRESS_FAMILY_UNSPECIFIED),
-      host_resolver_flags_(0),
-      allow_cached_response_(true),
-      only_use_cached_response_(false),
-      is_speculative_(false),
-      priority_(MEDIUM) {
-}
-
-HostResolver::~HostResolver() {
-}
-
-AddressFamily HostResolver::GetDefaultAddressFamily() const {
-  return ADDRESS_FAMILY_UNSPECIFIED;
-}
-
-HostResolverImpl* HostResolver::GetAsHostResolverImpl() {
-  return NULL;
-}
-
-HostResolver::HostResolver() {
-}
-
 SingleRequestHostResolver::SingleRequestHostResolver(HostResolver* resolver)
     : resolver_(resolver),
       cur_request_(NULL),
@@ -51,7 +27,7 @@
                                        AddressList* addresses,
                                        CompletionCallback* callback,
                                        const BoundNetLog& net_log) {
-  DCHECK(!cur_request_ && !cur_request_callback_) << "resolver already in use";
+  DCHECK(!cur_request_callback_) << "resolver already in use";
 
   HostResolver::RequestHandle request = NULL;
 
@@ -63,6 +39,7 @@
       info, addresses, transient_callback, &request, net_log);
 
   if (rv == ERR_IO_PENDING) {
+    DCHECK(callback);
     // Cleared in OnResolveCompletion().
     cur_request_ = request;
     cur_request_callback_ = callback;
@@ -72,9 +49,10 @@
 }
 
 void SingleRequestHostResolver::Cancel() {
-  if (cur_request_) {
+  if (cur_request_callback_) {
     resolver_->CancelRequest(cur_request_);
     cur_request_ = NULL;
+    cur_request_callback_ = NULL;
   }
 }