Switch the factory chunk in the skps to storing its size in bytes

include/core/SkPicture.h

Index: include/core/SkPicture.h
===================================================================
--- include/core/SkPicture.h	(revision 13672)
+++ include/core/SkPicture.h	(working copy)
@@ -250,13 +250,14 @@
     // V19: encode matrices and regions into the ops stream
     // V20: added bool to SkPictureImageFilter's serialization (to allow SkPicture serialization)
     // V21: add pushCull, popCull
+    // V22: SK_PICT_FACTORY_TAG's size is now the chunk size in bytes
 
     // Note: If the picture version needs to be increased then please follow the
     // steps to generate new SKPs in (only accessible to Googlers): http://goo.gl/qATVcw
 
     // Only SKPs within the min/current picture version range (inclusive) can be read.
     static const uint32_t MIN_PICTURE_VERSION = 19;
-    static const uint32_t CURRENT_PICTURE_VERSION = 21;
+    static const uint32_t CURRENT_PICTURE_VERSION = 22;
 
     // fPlayback, fRecord, fWidth & fHeight are protected to allow derived classes to
     // install their own SkPicturePlayback-derived players,SkPictureRecord-derived