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

Source/core/frame/LocalFrame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 223 matching lines @@
     visitor->trace(m_selection);
     visitor->trace(m_eventHandler);
     visitor->trace(m_console);
     visitor->trace(m_inputMethodController);
     visitor->registerWeakMembers<LocalFrame, &LocalFrame::clearWeakMembers>(this);
     HeapSupplementable<LocalFrame>::trace(visitor);
 #endif
     Frame::trace(visitor);
 }
 
-LocalDOMWindow* LocalFrame::domWindow() const
+DOMWindow* LocalFrame::domWindow() const

[haraken, 2014/11/08 09:17:25]

Can we remove this method?

DOMWindow* window = localFrame()->localDOMWindow();

will just work. It looks confusing to have both domWindow() and
localDOMWindow().

[dcheng, 2014/11/08 23:59:56]

The main reason we have localDOMWindow() is because I can't use covariant
returns for both LocalFrame::domWindow() and LocalDOMWindow::frame(), since this
would be a circular dependency. So instead, we expose the local version through
a non-virtual getter.

Unfortunately, removing either leads to uglier code elsewhere:
1. The reason we have this exposed as an overridable method on Frame is to
simplify code like DOMWindow::top(). Without this virtual, DOMWindow::top()
would have to look like:
    Frame* f = frame()->tree()->top();
    return f->isLocalFrame() ?
static_cast<DOMWindow*>(toLocalFrame(f)->localDOMWindow())
        : toRemoteFrame(f)->remoteDOMWindow();

2. The reason we have LocalFrame::localDOMWindow() is to prevent useless casts.
For example, DOMWindowProperty is always associated with a LocalFrame atm.
Without localDOMWindow(), the code would change from:
#if ENABLE(OILPAN)
        m_frame->localDOMWindow()->registerProperty(this);
#else
        m_associatedDOMWindow = m_frame->localDOMWindow();
        m_associatedDOMWindow->registerProperty(this);
#endif

to:
#if ENABLE(OILPAN)
        toLocalDOMWindow(m_frame->DOMWindow())->registerProperty(this);
#else
        m_associatedDOMWindow = toLocalDOMWindow(m_frame->localDOMWindow());
        m_associatedDOMWindow->registerProperty(this);
#endif

This cast is pointless, because we always have LocalFrames here, and LocalFrames
must have LocalDOMWindows.

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

Makes sense.

 {
     return m_domWindow.get();
 }
 
 void LocalFrame::navigate(Document& originDocument, const KURL& url, bool lockBackForwardList)
 {
     m_navigationScheduler.scheduleLocationChange(&originDocument, url.string(), lockBackForwardList);
 }
 
 void LocalFrame::detach()
@@ skipping 533 matching lines @@
     // We detach the FrameView's custom scroll bars as early as
     // possible to prevent m_doc->detach() from messing with the view
     // such that its scroll bars won't be torn down.
     //
     // FIXME: We should revisit this.
     if (m_view)
         m_view->prepareForDetach();
 }
 
 } // namespace blink