Add CHECKs to try to narrow down cause of bad internal fields in Window DOM wrapper

third_party/WebKit/Source/web/WebRemoteFrameImpl.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 "web/WebRemoteFrameImpl.h"
 
 #include "bindings/core/v8/RemoteWindowProxy.h"
+#include "bindings/core/v8/V8Window.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/RemoteSecurityContext.h"
 #include "core/dom/SecurityContext.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutObject.h"
 #include "core/page/Page.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/WebFloatRect.h"
 #include "public/platform/WebRect.h"
 #include "public/web/WebDocument.h"
 #include "public/web/WebFrameOwnerProperties.h"
 #include "public/web/WebPerformance.h"
 #include "public/web/WebRange.h"
 #include "public/web/WebTreeScopeType.h"
 #include "v8/include/v8.h"
 #include "web/RemoteFrameOwner.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebViewImpl.h"
+#include "wtf/debug/Alias.h"
 
 namespace blink {
 
 WebRemoteFrame* WebRemoteFrame::create(WebTreeScopeType scope,
                                        WebRemoteFrameClient* client,
                                        WebFrame* opener) {
   return WebRemoteFrameImpl::create(scope, client, opener);
 }
 
 WebRemoteFrameImpl* WebRemoteFrameImpl::create(WebTreeScopeType scope,
@@ skipping 169 matching lines @@
   return v8::Local<v8::Value>();
 }
 
 v8::Local<v8::Context> WebRemoteFrameImpl::mainWorldScriptContext() const {
   NOTREACHED();
   return v8::Local<v8::Context>();
 }
 
 v8::Local<v8::Context> WebRemoteFrameImpl::deprecatedMainWorldScriptContext()
     const {
-  return static_cast<RemoteWindowProxy*>(
-             frame()->windowProxy(DOMWrapperWorld::mainWorld()))
-      ->contextIfInitialized();
+  v8::Local<v8::Context> context =
+      static_cast<RemoteWindowProxy*>(
+          frame()->windowProxy(DOMWrapperWorld::mainWorld()))
+          ->contextIfInitialized();
+
+  DOMWindow* window = frame()->domWindow();
+  // Prevent this local from getting optimized out, and hopefully, the heap
+  // contents captured into minidumps.
+  WTF::debug::alias(&window);
+
+  v8::Local<v8::Object> globalProxy = context->Global();
+  CHECK(!globalProxy.IsEmpty());
+  CHECK(V8Window::hasInstance(globalProxy, v8::Isolate::GetCurrent()));
+  CHECK(window);
+  CHECK_EQ(window, V8Window::toImpl(globalProxy));
+
+  return context;
 }
 
 void WebRemoteFrameImpl::reload(WebFrameLoadType) {
   NOTREACHED();
 }
 
 void WebRemoteFrameImpl::reloadWithOverrideURL(const WebURL& overrideUrl,
                                                WebFrameLoadType) {
   NOTREACHED();
 }
@@ skipping 299 matching lines @@
 }
 
 WebRemoteFrameImpl::WebRemoteFrameImpl(WebTreeScopeType scope,
                                        WebRemoteFrameClient* client)
     : WebRemoteFrame(scope),
       m_frameClient(RemoteFrameClientImpl::create(this)),
       m_client(client),
       m_selfKeepAlive(this) {}
 
 }  // namespace blink