Revert of Use std::unique_ptr instead of rtc::scoped_refptr in AsyncInvoker.

webrtc/base/asyncinvoker-inl.h

 /*
  *  Copyright 2014 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_BASE_ASYNCINVOKER_INL_H_
 #define WEBRTC_BASE_ASYNCINVOKER_INL_H_
 
 #include "webrtc/base/bind.h"
 #include "webrtc/base/callback.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/messagehandler.h"
+#include "webrtc/base/refcount.h"
+#include "webrtc/base/scoped_ref_ptr.h"
 #include "webrtc/base/sigslot.h"
 #include "webrtc/base/thread.h"
 
 namespace rtc {
 
 class AsyncInvoker;
 
 // Helper class for AsyncInvoker. Runs a task and triggers a callback
-// on the calling thread if necessary.
-class AsyncClosure {
+// on the calling thread if necessary. Instances are ref-counted so their
+// lifetime can be independent of AsyncInvoker.
+class AsyncClosure : public RefCountInterface {
  public:
-  virtual ~AsyncClosure() {}
   // Runs the asynchronous task, and triggers a callback to the calling
   // thread if needed. Should be called from the target thread.
   virtual void Execute() = 0;
+ protected:
+  ~AsyncClosure() override {}
 };
 
 // Simple closure that doesn't trigger a callback for the calling thread.
 template <class FunctorT>
 class FireAndForgetAsyncClosure : public AsyncClosure {
  public:
   explicit FireAndForgetAsyncClosure(const FunctorT& functor)
       : functor_(functor) {}
   virtual void Execute() {
     functor_();
@@ skipping 83 matching lines @@
     TriggerCallback();
   }
 
  private:
   FunctorT functor_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_ASYNCINVOKER_INL_H_