[WIP] Adding support for <iframe>s to slimming paint.

Source/core/paint/DrawingRecorder.cpp

Index: Source/core/paint/DrawingRecorder.cpp
diff --git a/Source/core/paint/DrawingRecorder.cpp b/Source/core/paint/DrawingRecorder.cpp
index 35aada0788ab583a232f575d4e2a69d4d68b6e97..72ed5ab0da359a40aab4e3b4f42827eaf66ffd2c 100644
--- a/Source/core/paint/DrawingRecorder.cpp
+++ b/Source/core/paint/DrawingRecorder.cpp
@@ -53,8 +53,8 @@ DrawingRecorder::~DrawingRecorder()
     ASSERT(displayList->bounds() == m_bounds);
     OwnPtr<DrawingDisplayItem> drawingItem = adoptPtr(
         new DrawingDisplayItem(displayList->picture(), m_bounds.location(), m_phase, m_renderer));
-    ASSERT(m_renderer->view());
-    m_renderer->view()->viewDisplayList().add(drawingItem.release());
+
+    ViewDisplayList::fromRenderObject(m_renderer).add(drawingItem.release());

[chrishtr, 2014/11/01 23:44:10]

I hadn't mentioned it yet, but since your CL forces the issue, we should put the
DisplayItemList (and rename it to that instead of ViewDisplayList) on
paintInvalidationContainer->layer()->graphicsLayerBacking(). If we do that then
the rest we get for free, e.g. traversing across non-composited vs composited
iframes, or eventually turning off compositing below the root document entirely.


GraphicsLayer will also be the right entry point for sending the DisplayList to
cc as we implement the rest of Slimming Paint, and allow us to easily get to the
phase 1 launch point of painting existing cc::Layers w/Slimming Paint.

[trchen, 2014/11/02 10:36:46]

Ah ha, that makes sense. I will revise as you planned.

 }
 
 #ifndef NDEBUG