Attach a WebLayer to a frame element for out-of-process iframes.

Source/core/frame/Frame.h

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 19 matching lines @@
 
 #include "core/loader/FrameLoader.h"
 #include "core/loader/NavigationScheduler.h"
 #include "core/frame/AdjustViewSizeOrNot.h"
 #include "core/page/FrameTree.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "wtf/Forward.h"
 #include "wtf/RefCounted.h"
 
+namespace blink {
+class WebLayer;
+}
+
 namespace WebCore {
 
     class AnimationController;
     class ChromeClient;
     class Color;
     class DOMWindow;
     class Document;
     class DragImage;
     class Editor;
     class Element;
@@ skipping 95 matching lines @@
         ScriptController& script();
         SpellChecker& spellChecker() const;
 
         RenderView* contentRenderer() const; // Root of the render tree for the document contained in this frame.
         RenderPart* ownerRenderer() const; // Renderer for the element that contains this frame.
 
         void dispatchVisibilityStateChangeEvent();
 
         int64_t frameID() const { return m_frameInit->frameID(); }
 
+        void setPlatformLayer(blink::WebLayer* platformLayer) { m_platformLayer = platformLayer; }

[eseidel, 2013/12/11 18:50:01]

I would give this a less generic name.  setRemotePlatformLayer?

I would also ideally compile-time guard this and only have it on for OOPI
enabled builds.  We don't generally do large experiments like this on trunk
(e.g. oilpan).  OOPI's design doesn't seem solidified and we're still
experimenting here.

[ncarter (slow), 2013/12/11 21:28:11]

Is the oilpan comparison apt? I think our design is fairly solidified, but as
with all software development, the act of reducing the design to code will
involve some process of discovery and experimentation.

A compile-time guard puts a substantial burden on development: you now need a
custom builder for any kind of test automation, which in practice may mean that
we simply won't have tests running on trybots or builders until we are ready to
drop the #define. It also adds significant friction to switching a local build
into the OOPIF mode, which may inhibit our ability to successfully convince
domain experts to jump in and offer a hand in development.

In my opinion, protecting the codepath with a runtime flag would be a better
choice, provided of course that this is acceptable from a regression-risk
perspective.

+        blink::WebLayer* platformLayer() const { return m_platformLayer; }
+
     // ======== All public functions below this point are candidates to move out of Frame into another class. ========
 
         bool inScope(TreeScope*) const;
 
         // See GraphicsLayerClient.h for accepted flags.
         String layerTreeAsText(unsigned flags = 0) const;
         String trackedRepaintRectsAsText() const;
 
         Settings* settings() const; // can be NULL
 
@@ skipping 64 matching lines @@
         RefPtr<FrameInit> m_frameInit;
 
         float m_pageZoomFactor;
         float m_textZoomFactor;
 
 #if ENABLE(ORIENTATION_EVENTS)
         int m_orientation;
 #endif
 
         bool m_inViewSourceMode;
+
+        // This layer is for frames whose contents are being rendered in a separate process.

[eseidel, 2013/12/11 18:50:01]

You could just convey that in the member name.

[kenrb, 2013/12/11 22:44:56]

Done.

+        blink::WebLayer* m_platformLayer;
     };
 
     inline void Frame::init()
     {
         m_loader.init();
     }
 
     inline FrameLoader& Frame::loader() const
     {
         return m_loader;
@@ skipping 71 matching lines @@
 
     inline EventHandler& Frame::eventHandler() const
     {
         ASSERT(m_eventHandler);
         return *m_eventHandler;
     }
 
 } // namespace WebCore
 
 #endif // Frame_h