Create a GraphicsContext from a DisplayList.

Source/platform/graphics/GraphicsContext.h

Index: Source/platform/graphics/GraphicsContext.h
diff --git a/Source/platform/graphics/GraphicsContext.h b/Source/platform/graphics/GraphicsContext.h
index 8647e4f20b1bed5f77086090c4d321eb2cf424c9..40d1669a04882f1f1230d607aabed9f9f087ac3a 100644
--- a/Source/platform/graphics/GraphicsContext.h
+++ b/Source/platform/graphics/GraphicsContext.h
@@ -75,7 +75,12 @@ public:
         FullyDisabled = 1 // Do absolutely minimal work to remove the cost of the context from performance tests.
     };
 
+    // Create a context using an existing canvas.
     explicit GraphicsContext(SkCanvas*, DisabledMode = NothingDisabled);
+
+    // Create a context with a recording canvas of the given size, and beginRecording on it.
+    explicit GraphicsContext(const FloatRect&, DisabledMode = NothingDisabled);
+
     ~GraphicsContext();
 
     // Returns the canvas used for painting. Must not be called if painting is disabled.
@@ -425,6 +430,10 @@ private:
         return m_paintState;
     }
 
+    void initializeStateStack();
+
+    void beginRecordingImpl(PassRefPtr<DisplayList>, uint32_t, SkCanvas*, SkMatrix&);
+
     static void setPathFromConvexPoints(SkPath*, size_t, const FloatPoint*);
     static void setRadii(SkVector*, IntSize, IntSize, IntSize, IntSize);