Oilpan: Reduce the reserved size of CallbackStacks

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

Index: third_party/WebKit/Source/platform/heap/CallbackStack.h
diff --git a/third_party/WebKit/Source/platform/heap/CallbackStack.h b/third_party/WebKit/Source/platform/heap/CallbackStack.h
index 0d60ebc3da73d0ae7f40f3fdca1ab4f4db56057d..4d24b043b1bac49315fca35cf20b92596fc07353 100644
--- a/third_party/WebKit/Source/platform/heap/CallbackStack.h
+++ b/third_party/WebKit/Source/platform/heap/CallbackStack.h
@@ -37,7 +37,7 @@ public:
         VisitorCallback m_callback;
     };
 
-    CallbackStack();
+    explicit CallbackStack(size_t);
     ~CallbackStack();
 
     void clear();
@@ -54,39 +54,23 @@ public:
 #endif
 
 private:
-    static const size_t blockSize = 8192;
-
     class Block {
         USING_FAST_MALLOC(Block);
     public:
-        explicit Block(Block* next)
-            : m_limit(&(m_buffer[blockSize]))
-            , m_current(&(m_buffer[0]))
-            , m_next(next)
-        {
-            clearUnused();
-        }
-
-        ~Block()
-        {
-            clearUnused();
-        }
+        explicit Block(Block*, size_t);
+        ~Block();
 
         void clear();
 
         Block* next() const { return m_next; }
         void setNext(Block* next) { m_next = next; }
+        size_t blockSize() const { return m_blockSize; }
 
         bool isEmptyBlock() const
         {
             return m_current == &(m_buffer[0]);
         }
 
-        size_t size() const
-        {
-            return blockSize - (m_limit - m_current);
-        }
-
         Item* allocateEntry()
         {
             if (LIKELY(m_current < m_limit))
@@ -109,10 +93,11 @@ private:
     private:
         void clearUnused();
 
-        Item m_buffer[blockSize];
+        Item* m_buffer;
         Item* m_limit;
         Item* m_current;
         Block* m_next;
+        size_t m_blockSize;
     };
 
     Item* popSlow();