add SkDrawPictureCallback optional parameter to drawPicture(), which can abort the picture drawing.

include/core/SkPicture.h

Index: include/core/SkPicture.h
diff --git a/include/core/SkPicture.h b/include/core/SkPicture.h
index b2c2b62edec4ee3684dc4ef4ef3129a1e29f2ad8..f8ae9ecb4fe4e50cdad9e5e13b25d59608acecd6 100644
--- a/include/core/SkPicture.h
+++ b/include/core/SkPicture.h
@@ -15,6 +15,7 @@
 
 class SkBBoxHierarchy;
 class SkCanvas;
+class SkDrawPictureCallback;
 class SkPicturePlayback;
 class SkPictureRecord;
 class SkStream;
@@ -150,9 +151,9 @@ public:
 
     /** Replays the drawing commands on the specified canvas. This internally
         calls endRecording() if that has not already been called.
-        @param surface the canvas receiving the drawing commands.
+        @param canvas the canvas receiving the drawing commands.

[robertphillips, 2013/05/16 15:04:23]

// @param callback optional callback to abort drawing

     */
-    void draw(SkCanvas* surface);
+    void draw(SkCanvas* canvas, SkDrawPictureCallback* = NULL);
 
     /** Return the width of the picture's recording canvas. This
         value reflects what was passed to setSize(), and does not necessarily