postMessage(): transfer allocation costs along with value.

third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h

Index: third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h b/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
index ceb9d63e64389f54d7ef4cec4ed2bf23c86c38de..7580dbc0aa26a3ce330f60a36b30c6ca16fdc444 100644
--- a/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
+++ b/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
@@ -128,13 +128,21 @@ class CORE_EXPORT SerializedScriptValue
       const ImageBitmapArray&,
       ExceptionState&);
 
-  // Informs the V8 about external memory allocated and owned by this object.
+  // Informs V8 about external memory allocated and owned by this object.
   // Large values should contribute to GC counters to eventually trigger a GC,
   // otherwise flood of postMessage() can cause OOM.
   // Ok to invoke multiple times (only adds memory once).
   // The memory registration is revoked automatically in destructor.
   void registerMemoryAllocatedWithCurrentScriptContext();
 
+  // Upon passing a serialized value from one context to another (via a
+  // postMessage()), the allocation amounts it has registered with the
+  // 'origining' context must be discharged, as the 'target' context will assume
+  // ownership of value. This method takes care of the first part of the
+  // external allocation bookkeeping, the above registration method the other
+  // half.
+  void unregisterMemoryAllocatedByCurrentScriptContext();
+
   const uint8_t* data() const { return m_dataBuffer.get(); }
   size_t dataLengthInBytes() const { return m_dataBufferSize; }
 
@@ -179,7 +187,7 @@ class CORE_EXPORT SerializedScriptValue
   std::unique_ptr<ArrayBufferContentsArray> m_arrayBufferContentsArray;
   std::unique_ptr<ImageBitmapContentsArray> m_imageBitmapContentsArray;
   BlobDataHandleMap m_blobDataHandles;
-  intptr_t m_externallyAllocatedMemory;
+  int64_t m_externallyAllocatedMemory;
 };
 
 }  // namespace blink