add installPixels

include/core/SkPixelRef.h

Index: include/core/SkPixelRef.h
diff --git a/include/core/SkPixelRef.h b/include/core/SkPixelRef.h
index fc0feb042adb59a2e5ff002e5f181b3375d5a65a..e65f4a04c5b5e1538c291e69ff1d1d920130f82f 100644
--- a/include/core/SkPixelRef.h
+++ b/include/core/SkPixelRef.h
@@ -364,4 +364,15 @@ private:
     typedef SkFlattenable INHERITED;
 };
 
+class SkPixelRefFactory : public SkRefCnt {
+public:
+    /**
+     *  Allocate a new pixelref matching the specified ImageInfo, allocating
+     *  the memory for the pixels. If the ImageInfo requires a ColorTable,
+     *  the pixelref will ref() the colortable.
+     *  On failure return NULL.
+     */
+    virtual SkPixelRef* create(const SkImageInfo&, SkColorTable*) = 0;
+};
+
 #endif