Basic windowless plugins, try 2.

skia/ext/bitmap_platform_device_linux.h

Index: skia/ext/bitmap_platform_device_linux.h
diff --git a/skia/ext/bitmap_platform_device_linux.h b/skia/ext/bitmap_platform_device_linux.h
index d26c50d72a7faebcd3dfa93f5cf199b22028727b..bb261bd8c3623cb4d75526458d7b6c16fb550299 100644
--- a/skia/ext/bitmap_platform_device_linux.h
+++ b/skia/ext/bitmap_platform_device_linux.h
@@ -85,6 +85,10 @@ class BitmapPlatformDeviceLinux : public PlatformDeviceLinux {
   // Bitmaps aren't vector graphics.
   virtual bool IsVectorial() { return false; }
 
+  // If someone wants to paint on a Cairo surface version of our
+  // buffer, then give them the surface we're already using.
+  virtual cairo_surface_t* beginPlatformPaint() { return surface(); }
+
   cairo_surface_t* surface() const;
 
  private: