Use the current context as the creation context for cross-origin objects.

third_party/WebKit/Source/core/frame/Location.cpp

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 13 matching lines @@
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/frame/Location.h"
 
 #include "bindings/core/v8/BindingSecurity.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8DOMActivityLogger.h"
+#include "bindings/core/v8/V8DOMWrapper.h"
 #include "core/dom/DOMURLUtilsReadOnly.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/loader/FrameLoader.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/SecurityOrigin.h"
 
 namespace blink {
@@ skipping 68 matching lines @@
   DOMStringList* origins = DOMStringList::create();
   if (!m_frame)
     return origins;
   for (Frame* frame = m_frame->tree().parent(); frame;
        frame = frame->tree().parent()) {
     origins->append(frame->securityContext()->getSecurityOrigin()->toString());
   }
   return origins;
 }
 
+v8::Local<v8::Object> Location::crossOriginWrapper(v8::Isolate* isolate) {

[Yuki, 2017/01/24 10:31:05]

I guess it's better to rename this function to remoteFrameWrapper?

+  if (m_crossOriginWrapper.IsEmpty()) {
+    m_crossOriginWrapper.Reset(
+        isolate, wrapperTypeInfo()
+                     ->domTemplate(isolate, DOMWrapperWorld::world(

[dcheng, 2017/01/24 09:40:47]

However, this makes me nervous. Is there a way to get a dom template that's not
associated with a world?

[Yuki, 2017/01/24 10:31:04]

No, because we have main-world-specific optimization in v8::FunctionTempalte and
its prototype template.  And this seems incorrect that we're going to use the
same v8::Object between the main world and isolated worlds.  We're going to
assume "it's in the main world" even if it's in an isolated world.

Do we really need to re-use the existing Location::wrapperTypeInfo() here?  Is
it okay to define a new WrapperTypeInfo dedicated for remote frames?

[dcheng, 2017/01/24 10:41:59]

Can you point me at the main world optimizations? I'm curious to see if it will
affect the correctness of doing this. I saw several in things like DOMDataStore,
but I want to make sure I'm looking at the right ones.

[Yuki, 2017/01/24 10:53:00]

I meant [PerWorldBindings] extended attribute, but Location.idl seems not having
it.  So probably it actually works.  But it's unfortunate to ignore worlds.

If you support things in handlers, I guess you wouldn't need much contents in
v8::FunctionTemplate?

If this approach works fine, I'm not insisting to
v8::FunctionTemplate::GetFunction.

+                                                isolate->GetCurrentContext()))
+                     ->NewRemoteInstance()

[dcheng, 2017/01/24 09:40:47]

+jochen

Sharing a remote instance like this should be safe, right? The access checks
should prevent access to anything 'interesting'. The main thing I'm worried
about is things in the prototype chain leaking between worlds / contexts, but I
think NewRemoteInstance() should be designed with that in mind, since it doesn't
use the current context?

[Yuki, 2017/01/24 10:31:04]

If it's okay, then I'd like to have a comment here to say that it's okay to
share the same v8::Object among contexts of remote frames.

+                     .ToLocalChecked());
+    V8DOMWrapper::setNativeInfo(isolate, m_crossOriginWrapper.Get(isolate),
+                                wrapperTypeInfo(), this);
+    m_crossOriginWrapper.SetWrapperClassId(wrapperTypeInfo()->wrapperClassId);
+  }
+  return m_crossOriginWrapper.Get(isolate);
+}
+
 String Location::hash() const {
   if (!m_frame)
     return String();
 
   return DOMURLUtilsReadOnly::hash(url());
 }
 
 void Location::setHref(LocalDOMWindow* currentWindow,
                        LocalDOMWindow* enteredWindow,
                        const String& url,
@@ skipping 180 matching lines @@
     argv.push_back(enteredDocument->url());
     argv.push_back(completedURL);
     activityLogger->logEvent("blinkSetAttribute", argv.size(), argv.data());
   }
   m_frame->navigate(*currentWindow->document(), completedURL,
                     setLocationPolicy == SetLocationPolicy::ReplaceThisFrame,
                     UserGestureStatus::None);
 }
 
 }  // namespace blink