Keep the cairo clipping region in sync with the Skia one.

skia/ext/bitmap_platform_device_win.h

Index: skia/ext/bitmap_platform_device_win.h
diff --git a/skia/ext/bitmap_platform_device_win.h b/skia/ext/bitmap_platform_device_win.h
index b37792a90de60fea66e2f8bdf3f3d1dbd5bdb5d0..7093ff180e7d3672664a7bf089860d517045c9fb 100644
--- a/skia/ext/bitmap_platform_device_win.h
+++ b/skia/ext/bitmap_platform_device_win.h
@@ -64,6 +64,9 @@ class BitmapPlatformDevice : public PlatformDevice {
   // Retrieves the bitmap DC, which is the memory DC for our bitmap data. The
   // bitmap DC is lazy created.
   virtual HDC getBitmapDC();
+
+  // Loads the given transform and clipping region into the HDC. This is
+  // overridden from SkDevice.
   virtual void setMatrixClip(const SkMatrix& transform, const SkRegion& region);
 
   virtual void drawToHDC(HDC dc, int x, int y, const RECT* src_rect);