Reset ThreadState weak callback stack before GCing.

third_party/WebKit/Source/platform/heap/CallbackStack.cpp

 // Copyright 2014 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 "platform/heap/CallbackStack.h"
 #include "wtf/allocator/PageAllocator.h"
 
 namespace blink {
 
 size_t const CallbackStack::kMinimalBlockSize = WTF::kPageAllocationGranularity / sizeof(CallbackStack::Item);
@@ skipping 27 matching lines @@
 #if ENABLE(ASSERT)
 void CallbackStack::Block::clear()
 {
     for (size_t i = 0; i < m_blockSize; i++)
         m_buffer[i] = Item(0, 0);
 }
 #endif
 
 void CallbackStack::Block::decommit()
 {
+    reset();
+    WTF::discardSystemPages(m_buffer, m_blockSize * sizeof(Item));
+}
+
+void CallbackStack::Block::reset()
+{
 #if ENABLE(ASSERT)
     clear();
 #endif
-    WTF::discardSystemPages(m_buffer, m_blockSize * sizeof(Item));
-
     m_current = &m_buffer[0];
     m_next = nullptr;
 }
 
 void CallbackStack::Block::invokeEphemeronCallbacks(Visitor* visitor)
 {
     // This loop can tolerate entries being added by the callbacks after
     // iteration starts.
     for (unsigned i = 0; m_buffer + i < m_current; i++) {
         Item& item = m_buffer[i];
@@ skipping 20 matching lines @@
 }
 
 CallbackStack::~CallbackStack()
 {
     RELEASE_ASSERT(isEmpty());
     delete m_first;
     m_first = nullptr;
     m_last = nullptr;
 }
 
+void CallbackStack::clear()
+{
+    Block* next;
+    for (Block* current = m_first->next(); current; current = next) {
+        next = current->next();
+        delete current;
+    }
+    m_first->reset();
+    m_last = m_first;
+}
+
 void CallbackStack::decommit()
 {
     Block* next;
     for (Block* current = m_first->next(); current; current = next) {
         next = current->next();
         delete current;
     }
     m_first->decommit();
     m_last = m_first;
 }
@@ skipping 67 matching lines @@
 {
     for (Block* current = m_first; current; current = current->next()) {
         if (current->hasCallbackForObject(object))
             return true;
     }
     return false;
 }
 #endif
 
 } // namespace blink