Reduce ephemeron stack size reservation.

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

 // 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.
 
 #ifndef CallbackStack_h
 #define CallbackStack_h
 
-#include "platform/heap/ThreadState.h"
+#include "platform/heap/BlinkGC.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 // The CallbackStack contains all the visitor callbacks used to trace and mark
 // objects. A specific CallbackStack instance contains at most bufferSize elements.
 // If more space is needed a new CallbackStack instance is created and chained
 // together with the former instance. I.e. a logical CallbackStack can be made of
 // multiple chained CallbackStack object instances.
@@ skipping 28 matching lines @@
     Item* pop();
 
     bool isEmpty() const;
 
     void invokeEphemeronCallbacks(Visitor*);
 
 #if ENABLE(ASSERT)
     bool hasCallbackForObject(const void*);
 #endif
 
+    static const size_t kMinimalBlockSize;
+
 private:
     static const size_t defaultBlockSize = (1 << 13);
 
     class Block {
         USING_FAST_MALLOC(Block);
     public:
         Block(Block* next, size_t blockSize);
         ~Block();
 
 #if ENABLE(ASSERT)
@@ skipping 63 matching lines @@
     Item* item = m_first->pop();
     if (LIKELY(!!item))
         return item;
 
     return popSlow();
 }
 
 } // namespace blink
 
 #endif // CallbackStack_h