Extract a DOMWindow interface from LocalDOMWindow and use it in the idl.

Source/core/events/MouseRelatedEvent.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 22 matching lines @@
 namespace blink {
 
 MouseRelatedEvent::MouseRelatedEvent()
     : m_isSimulated(false)
     , m_hasCachedRelativePosition(false)
 {
 }
 
 static LayoutSize contentsScrollOffset(AbstractView* abstractView)
 {
-    if (!abstractView)
+    if (!abstractView || !abstractView->isLocalDOMWindow())

[haraken, 2014/11/10 08:58:20]

Is it OK to return LayoutSize() for a RemoteDOMWindow?

[dcheng, 2014/11/10 09:29:43]

This code is hit on the path for initMouseEvent(). Since JS can pass any window
to initMouseEvent(), it could pass a window for a frame that is remote. I think
you could argue that the current implementation is actually an info leak. I
think you could potentially use it to detect page zoom across origins--pass a
cross-origin Window object to initMouseEvent() and observe how the
clientX/clientY coordinates change from the supplied values. In that respect, I
think that returning LayoutSize() is reasonable here.

         return LayoutSize();
-    LocalFrame* frame = abstractView->frame();
+    LocalFrame* frame = toLocalDOMWindow(abstractView)->frame();
     if (!frame)
         return LayoutSize();
     FrameView* frameView = frame->view();
     if (!frameView)
         return LayoutSize();
     float scaleFactor = frame->pageZoomFactor();
     return LayoutSize(frameView->scrollX() / scaleFactor, frameView->scrollY() / scaleFactor);
 }
 
 MouseRelatedEvent::MouseRelatedEvent(const AtomicString& eventType, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView> abstractView,
                                      int detail, const IntPoint& screenLocation, const IntPoint& windowLocation,
                                      const IntPoint& movementDelta,
                                      bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, bool isSimulated)
     : UIEventWithKeyState(eventType, canBubble, cancelable, abstractView, detail, ctrlKey, altKey, shiftKey, metaKey)
     , m_screenLocation(screenLocation)
     , m_movementDelta(movementDelta)
     , m_isSimulated(isSimulated)
 {
     LayoutPoint adjustedPageLocation;
     LayoutPoint scrollPosition;
 
-    LocalFrame* frame = view() ? view()->frame() : 0;
+    LocalFrame* frame = view() && view()->isLocalDOMWindow() ? toLocalDOMWindow(view())->frame() : 0;

[dcheng, 2014/11/10 09:29:43]

Note: looking at more code, I'm not sure if we can actually get a
RemoteDOMWindow here. I will probably change this to just call
toLocalDOMWindow() directly for the time being, and see if we get any errors
with the --site-per-process flag.

[dcheng, 2014/11/10 20:41:55]

Actually it turns out this is web-exposed:
https://code.google.com/p/chromium/codesearch#chromium/src/out/Debug/gen/blin...

UIEventInit/MouseEventInit can pass a user-supplied DOMWindow back to us. So we
can't eliminate this check =(

     if (frame && !isSimulated) {
         if (FrameView* frameView = frame->view()) {
             scrollPosition = frameView->scrollPosition();
             adjustedPageLocation = frameView->windowToContents(windowLocation);
             float scaleFactor = 1 / frame->pageZoomFactor();
             if (scaleFactor != 1.0f) {
                 adjustedPageLocation.scale(scaleFactor, scaleFactor);
                 scrollPosition.scale(scaleFactor, scaleFactor);
             }
         }
@@ skipping 25 matching lines @@
 
     m_layerLocation = m_pageLocation;
     m_offsetLocation = m_pageLocation;
 
     computePageLocation();
     m_hasCachedRelativePosition = false;
 }
 
 static float pageZoomFactor(const UIEvent* event)
 {
-    LocalDOMWindow* window = event->view();
-    if (!window)
+    if (!event->view() || !event->view()->isLocalDOMWindow())

[haraken, 2014/11/10 08:58:20]

Is it OK to return 1 for a RemoteDOMWindow?

[dcheng, 2014/11/10 09:29:43]

This is similar to my previous comment.

         return 1;
-    LocalFrame* frame = window->frame();
+    LocalFrame* frame = toLocalDOMWindow(event->view())->frame();
     if (!frame)
         return 1;
     return frame->pageZoomFactor();
 }
 
 void MouseRelatedEvent::computePageLocation()
 {
     float scaleFactor = pageZoomFactor(this);
     setAbsoluteLocation(roundedLayoutPoint(FloatPoint(pageX() * scaleFactor, pageY() * scaleFactor)));
 }
@@ skipping 97 matching lines @@
     // See Microsoft documentation and <http://www.quirksmode.org/dom/w3c_events.html>.
     return m_clientLocation.y();
 }
 
 void MouseRelatedEvent::trace(Visitor* visitor)
 {
     UIEventWithKeyState::trace(visitor);
 }
 
 } // namespace blink