Improve window.closed fidelity.

Source/core/frame/DOMWindow.cpp

 // 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.
 
 #include "config.h"
 #include "core/frame/DOMWindow.h"
 
 #include "bindings/core/v8/ScriptCallStackFactory.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/SecurityContext.h"
 #include "core/events/MessageEvent.h"
 #include "core/frame/Frame.h"
 #include "core/frame/FrameClient.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/Location.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/inspector/ScriptCallStack.h"
 #include "core/loader/MixedContentChecker.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/SecurityOrigin.h"
 
 namespace blink {
 
+DOMWindow::DOMWindow()
+    : m_windowIsClosing(false)
+{
+}
+
 DOMWindow::~DOMWindow()
 {
 }
 
 Location* DOMWindow::location() const
 {
     if (!m_location)
         m_location = Location::create(frame());
     return m_location.get();
 }
 
 bool DOMWindow::closed() const
 {
-    return !frame() || !frame()->host();
+    return m_windowIsClosing || !frame() || !frame()->host();

[haraken, 2015/04/05 15:06:36]

Do we still need the '!frame() || !frame()->host()' part?

[sof, 2015/04/05 15:09:42]

Yes, windows.close() is just the programmatic way to discard a browsing context.
(closed == true when that context is discarded.)

 }
 
 unsigned DOMWindow::length() const
 {
     return frame() ? frame()->tree().scopedChildCount() : 0;
 }
 
 DOMWindow* DOMWindow::self() const
 {
     if (!frame())
@@ skipping 130 matching lines @@
     }
 }
 
 DEFINE_TRACE(DOMWindow)
 {
     visitor->trace(m_location);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace blink