Assert sequence validity on non-thread-safe RefCount manipulations (2)

base/memory/ref_counted.cc

 // Copyright (c) 2011 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/memory/ref_counted.h"
+
 #include "base/threading/thread_collision_warner.h"
 
 namespace base {
+namespace {
+
+#if DCHECK_IS_ON()
+AtomicRefCount g_cross_thread_ref_count_access_allow_count = 0;
+#endif
+
+}  // namespace
 
 namespace subtle {
 
 bool RefCountedThreadSafeBase::HasOneRef() const {
   return AtomicRefCountIsOne(&ref_count_);
 }
 
 RefCountedThreadSafeBase::RefCountedThreadSafeBase() = default;
 
 RefCountedThreadSafeBase::~RefCountedThreadSafeBase() {
@@ skipping 17 matching lines @@
 #endif
   if (!AtomicRefCountDec(&ref_count_)) {
 #if DCHECK_IS_ON()
     in_dtor_ = true;
 #endif
     return true;
   }
   return false;
 }
 
+#if DCHECK_IS_ON()
+bool RefCountedBase::CalledOnValidSequence() const {
+  return sequence_checker_.CalledOnValidSequence() ||
+         !AtomicRefCountIsZero(&g_cross_thread_ref_count_access_allow_count);
+}
+#endif
+
 }  // namespace subtle
 
+#if DCHECK_IS_ON()
+ScopedAllowCrossThreadRefCountAccess::ScopedAllowCrossThreadRefCountAccess() {
+  AtomicRefCountInc(&g_cross_thread_ref_count_access_allow_count);
+}
+
+ScopedAllowCrossThreadRefCountAccess::~ScopedAllowCrossThreadRefCountAccess() {
+  AtomicRefCountDec(&g_cross_thread_ref_count_access_allow_count);
+}
+#endif
+
 }  // namespace base