Accurate transfer of SerializedScriptValue allocation costs.

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 e74e3dfd8b5f3a190600d1d26a335f5663dd7ab5..e62beb43276575356555856fcc55b703fd4668a5 100644
--- a/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
+++ b/third_party/WebKit/Source/bindings/core/v8/SerializedScriptValue.h
@@ -139,10 +139,24 @@ class CORE_EXPORT SerializedScriptValue
   // 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();
+  // ownership of the value. As we're potentially working across threads, this
+  // transfer of cost is handled in three stages:
+  //
+  //  - prepareForTransferringContext(): prepares and marks this
+  //    SerializedScriptValue as being destined for transfer to another
+  //    context.
+  //  - finalizeTransferringContext(): checks if the transfer was successful,
+  //    and if so, discounts allocation costs from the context just left.
+  //  - registerMemoryAllocatedWithCurrentScriptContext() - called by the
+  //    'target' once ownership has been assumed. It registers the allocation
+  //    costs of the resources that the SerializedScriptValue holds onto in
+  //    that new context.
+  //
+  // The first two are called by 'origining' context, before and after actual
+  // transfer.
+  //
+  void prepareForTransferringContext();
+  void finalizeTransferringContext();
 
   const uint8_t* data() const { return m_dataBuffer.get(); }
   size_t dataLengthInBytes() const { return m_dataBufferSize; }