Move asserts for tracking global object detachment to WindowProxy.

third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp

Index: third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp b/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
index efad7d6a828fab92d52b9714bba693e4a4a80078..f8bd774d197d965e457b44c890cc8c3eb991718e 100644
--- a/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp
@@ -92,6 +92,10 @@ void LocalWindowProxy::disposeContext(GlobalDetachmentBehavior behavior) {
     }
     V8DOMWrapper::clearNativeInfo(isolate(), context->Global());
     m_scriptState->detachGlobalObject();
+
+#if DCHECK_IS_ON()
+    didDetachGlobalProxy();

[Yuki, 2017/03/09 07:15:17]

nit: Is this name appropriate?

The old implementation was tracking that a global object gets detached from a
global proxy.  didDetachGlobalProxy sounds like we're detaching a global proxy
rather than global object.  It looks weird to me.

[dcheng, 2017/03/09 07:19:56]

Hmm... so what we want to track here is that the fields on the global proxy were
cleared. If you have other suggestions for what to call this, I'm open to ideas.

[Yuki, 2017/03/09 07:26:31]

A global object of V8 must be tightly bound to a DOMWindow instance of Blink, so
it should be equivalent to track the detachment of a global object.

But if we want to emphasize the internal fields, we can call it
didDetachDOMWindow(Instance), didDetachGlobalAndDOMWindow or something like
that.

Anyway, I'm thinking we're detaching something from a global proxy, not a global
proxy from something, because we keep the global proxy as m_globalProxy.

[dcheng, 2017/03/09 08:00:52]

Remote contexts have an inner global object, so that receiver lookup when using
v8::Signature works. However, remote contexts don't (currently) have an
equivalent concept of global object detachment.
OK, makes sense. Renamed it to didDetachGlobalObject(). I'll figure out a way to
make the semantics work for a remote context.

+#endif
   }
 
   m_scriptState->disposePerContextData();
@@ -211,6 +215,10 @@ void LocalWindowProxy::setupWindowPrototypeChain() {
   // reference to the DOMWindow.
   m_globalProxy.get().SetWrapperClassId(wrapperTypeInfo->wrapperClassId);
 
+#if DCHECK_IS_ON()
+  didAttachGlobalProxy();
+#endif
+
   // The global object, aka window wrapper object.
   v8::Local<v8::Object> windowWrapper =
       globalProxy->GetPrototype().As<v8::Object>();