Start BindStateBase ref count from 1 instead of 0

base/callback_internal.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 "base/callback_internal.h"
 
 #include "base/logging.h"
 
 namespace base {
 namespace internal {
 
 namespace {
 
 bool ReturnFalse(const BindStateBase*) {
   return false;
 }
 
 }  // namespace
 
+bool BindStateBase::HasOneRef() const {
+  return AtomicRefCountIsOne(&ref_count_);
+}
+
 BindStateBase::BindStateBase(InvokeFuncStorage polymorphic_invoke,
                              void (*destructor)(const BindStateBase*))
     : BindStateBase(polymorphic_invoke, destructor, &ReturnFalse) {
 }
 
 BindStateBase::BindStateBase(InvokeFuncStorage polymorphic_invoke,
                              void (*destructor)(const BindStateBase*),
                              bool (*is_cancelled)(const BindStateBase*))
     : polymorphic_invoke_(polymorphic_invoke),
-      ref_count_(0),
+      ref_count_(1),
       destructor_(destructor),
       is_cancelled_(is_cancelled) {}
 
 void BindStateBase::AddRef() const {
+#if DCHECK_IS_ON()
+  AtomicRefCount ref_count = subtle::Barrier_AtomicIncrement(&ref_count_, 1);
+  DCHECK_NE(1, ref_count);
+#else
   AtomicRefCountInc(&ref_count_);
+#endif
 }
 
 void BindStateBase::Release() const {
   if (!AtomicRefCountDec(&ref_count_))
     destructor_(this);
 }
 
 CallbackBase<CopyMode::MoveOnly>::CallbackBase(CallbackBase&& c) = default;
 
 CallbackBase<CopyMode::MoveOnly>&
@@ skipping 18 matching lines @@
 bool CallbackBase<CopyMode::MoveOnly>::IsCancelled() const {
   DCHECK(bind_state_);
   return bind_state_->IsCancelled();
 }
 
 bool CallbackBase<CopyMode::MoveOnly>::EqualsInternal(
     const CallbackBase& other) const {
   return bind_state_ == other.bind_state_;
 }
 
-CallbackBase<CopyMode::MoveOnly>::CallbackBase(
-    BindStateBase* bind_state)
-    : bind_state_(bind_state) {
+CallbackBase<CopyMode::MoveOnly>::CallbackBase(BindStateBase* bind_state)
+    : bind_state_(AdoptRef(bind_state)) {
   DCHECK(!bind_state_.get() || bind_state_->ref_count_ == 1);
 }
 
 CallbackBase<CopyMode::MoveOnly>::~CallbackBase() {}
 
 CallbackBase<CopyMode::Copyable>::CallbackBase(
     const CallbackBase& c)
     : CallbackBase<CopyMode::MoveOnly>(nullptr) {
   bind_state_ = c.bind_state_;
 }
 
 CallbackBase<CopyMode::Copyable>::CallbackBase(CallbackBase&& c) = default;
 
 CallbackBase<CopyMode::Copyable>&
 CallbackBase<CopyMode::Copyable>::operator=(const CallbackBase& c) {
   bind_state_ = c.bind_state_;
   return *this;
 }
 
 CallbackBase<CopyMode::Copyable>&
 CallbackBase<CopyMode::Copyable>::operator=(CallbackBase&& c) = default;
 
 template class CallbackBase<CopyMode::MoveOnly>;
 template class CallbackBase<CopyMode::Copyable>;
 
 }  // namespace internal
 }  // namespace base