Revert of Delete SignalThread class.

webrtc/rtc_base/nethelpers.h

 /*
  *  Copyright 2008 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_RTC_BASE_NETHELPERS_H_
 #define WEBRTC_RTC_BASE_NETHELPERS_H_
 
 #if defined(WEBRTC_POSIX)
 #include <netdb.h>
 #include <stddef.h>
 #elif WEBRTC_WIN
 #include <winsock2.h>  // NOLINT
 #endif
 
 #include <list>
-#include <memory>
 
 #include "webrtc/rtc_base/asyncresolverinterface.h"
-#include "webrtc/rtc_base/refcount.h"
-#include "webrtc/rtc_base/scoped_ref_ptr.h"
+#include "webrtc/rtc_base/signalthread.h"
 #include "webrtc/rtc_base/sigslot.h"
 #include "webrtc/rtc_base/socketaddress.h"
-#include "webrtc/rtc_base/thread_checker.h"
 
 namespace rtc {
 
-class Thread;
-class TaskQueue;
+class AsyncResolverTest;
 
-// AsyncResolver will perform async DNS resolution, signaling the result on the
-// SignalDone from AsyncResolverInterface when the operation completes.
-// SignalDone is fired on the same thread on which the AsyncResolver was
-// constructed.
-class AsyncResolver : public AsyncResolverInterface {
+// AsyncResolver will perform async DNS resolution, signaling the result on
+// the SignalDone from AsyncResolverInterface when the operation completes.
+class AsyncResolver : public SignalThread, public AsyncResolverInterface {
  public:
   AsyncResolver();
   ~AsyncResolver() override;
 
   void Start(const SocketAddress& addr) override;
   bool GetResolvedAddress(int family, SocketAddress* addr) const override;
   int GetError() const override;
   void Destroy(bool wait) override;
 
   const std::vector<IPAddress>& addresses() const { return addresses_; }
+  void set_error(int error) { error_ = error; }
+
+ protected:
+  void DoWork() override;
+  void OnWorkDone() override;
 
  private:
-  void ResolveDone(int error, std::vector<IPAddress> addresses);
-
-  class Trampoline : public RefCountInterface {
-   public:
-    Trampoline(AsyncResolver* resolver) : resolver(resolver) {}
-    // Points back to the resolver, as long as it is alive. Cleared
-    // by the AsyncResolver destructor.
-    AsyncResolver* resolver;
-  };
-
-  // |state_| is non-null while resolution is pending, i.e., set
-  // non-null by Start() and cleared by ResolveDone(). The destructor
-  // clears state_->resolver (assuming |state_| is non-null), to
-  // indicate that the resolver can no longer be accessed.
-  scoped_refptr<Trampoline> state_ ACCESS_ON(construction_thread_);
-
-  Thread* const construction_thread_;
-  // Set to true when Destroy() can't delete the object immediately.
-  // Indicate that the ResolveDone method is now responsible for
-  // deletion. method should delete the object.
-  bool destroyed_ = false;
-  // Queue used only for a single task.
-  std::unique_ptr<TaskQueue> resolver_queue_;
   SocketAddress addr_;
   std::vector<IPAddress> addresses_;
-  int error_ = -1;
+  int error_;
 };
 
 // rtc namespaced wrappers for inet_ntop and inet_pton so we can avoid
 // the windows-native versions of these.
 const char* inet_ntop(int af, const void *src, char* dst, socklen_t size);
 int inet_pton(int af, const char* src, void *dst);
 
 bool HasIPv4Enabled();
 bool HasIPv6Enabled();
 }  // namespace rtc
 
 #endif  // WEBRTC_RTC_BASE_NETHELPERS_H_