Add new skpinfo tool

src/core/SkPicturePlayback.h

Index: src/core/SkPicturePlayback.h
===================================================================
--- src/core/SkPicturePlayback.h	(revision 13640)
+++ src/core/SkPicturePlayback.h	(working copy)
@@ -45,6 +45,21 @@
     uint32_t    fFlags;
 };
 
+#define SK_PICT_READER_TAG     SkSetFourByteTag('r', 'e', 'a', 'd')
+#define SK_PICT_FACTORY_TAG    SkSetFourByteTag('f', 'a', 'c', 't')
+#define SK_PICT_TYPEFACE_TAG   SkSetFourByteTag('t', 'p', 'f', 'c')
+#define SK_PICT_PICTURE_TAG    SkSetFourByteTag('p', 'c', 't', 'r')
+
+// This tag specifies the size of the ReadBuffer, needed for the following tags
+#define SK_PICT_BUFFER_SIZE_TAG     SkSetFourByteTag('a', 'r', 'a', 'y')
+// these are all inside the ARRAYS tag
+#define SK_PICT_BITMAP_BUFFER_TAG  SkSetFourByteTag('b', 't', 'm', 'p')
+#define SK_PICT_PAINT_BUFFER_TAG   SkSetFourByteTag('p', 'n', 't', ' ')
+#define SK_PICT_PATH_BUFFER_TAG    SkSetFourByteTag('p', 't', 'h', ' ')
+
+// Always write this guy last (with no length field afterwards)
+#define SK_PICT_EOF_TAG     SkSetFourByteTag('e', 'o', 'f', ' ')
+
 /**
  * Container for data that is needed to deep copy a SkPicture. The container
  * enables the data to be generated once and reused for subsequent copies.