Adds clearer function to create rtc::Thread without Physical SocketServer

webrtc/base/thread.h

 /*
  *  Copyright 2004 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.
  */
 
@@ skipping 77 matching lines @@
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(Runnable);
 };
 
 // WARNING! SUBCLASSES MUST CALL Stop() IN THEIR DESTRUCTORS!  See ~Thread().
 
 class Thread : public MessageQueue {
  public:
   // Create a new Thread and optionally assign it to the passed SocketServer.
-  // Subclasses that override Clear should pass false for init_queue and call
-  // DoInit() from their constructor to prevent races with the
-  // MessageQueueManager already using the object while the vtable is still
-  // being created.
-  explicit Thread(SocketServer* ss = nullptr, bool init_queue = true);
+  Thread();
+  explicit Thread(SocketServer* ss);
+  explicit Thread(std::unique_ptr<SocketServer> ss);
 
   // NOTE: ALL SUBCLASSES OF Thread MUST CALL Stop() IN THEIR DESTRUCTORS (or
   // guarantee Stop() is explicitly called before the subclass is destroyed).
   // This is required to avoid a data race between the destructor modifying the
   // vtable, and the Thread::PreRun calling the virtual method Run().
   ~Thread() override;
 
+  static std::unique_ptr<Thread> CreateWithSocketServer();
+  static std::unique_ptr<Thread> Create();
   static Thread* Current();
 
   // Used to catch performance regressions. Use this to disallow blocking calls
   // (Invoke) for a given scope.  If a synchronous call is made while this is in
   // effect, an assert will be triggered.
   // Note that this is a single threaded class.
   class ScopedDisallowBlockingCalls {
    public:
     ScopedDisallowBlockingCalls();
     ~ScopedDisallowBlockingCalls();
@@ skipping 164 matching lines @@
 
   RTC_DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 // AutoThread automatically installs itself at construction
 // uninstalls at destruction, if a Thread object is
 // _not already_ associated with the current OS thread.
 
 class AutoThread : public Thread {
  public:
-  explicit AutoThread(SocketServer* ss = nullptr);
+  AutoThread();
   ~AutoThread() override;
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(AutoThread);
 };
 
 // Win32 extension for threads that need to use COM
 #if defined(WEBRTC_WIN)
 class ComThread : public Thread {
  public:
@@ skipping 21 matching lines @@
 
  private:
   SocketServer* old_ss_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SocketServerScope);
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_THREAD_H_