Adding SkSurface support to SkDeferredCanvas

include/utils/SkDeferredCanvas.h

Index: include/utils/SkDeferredCanvas.h
===================================================================
--- include/utils/SkDeferredCanvas.h	(revision 8622)
+++ include/utils/SkDeferredCanvas.h	(working copy)
@@ -12,6 +12,8 @@
 #include "SkPixelRef.h"
 
 class DeferredDevice;
+class SkImage;
+class SkSurface;
 
 /** \class SkDeferredCanvas
     Subclass of SkCanvas that encapsulates an SkPicture or SkGPipe for deferred
@@ -33,6 +35,12 @@
     */
     explicit SkDeferredCanvas(SkDevice* device);
 
+    /** Construct a canvas with the specified surface to draw into.
+        This constructor must be used for newImageSnapshot to work.
+        @param surface Specifies a surface for the canvas to draw into.
+    */
+    explicit SkDeferredCanvas(SkSurface* surface);
+
     virtual ~SkDeferredCanvas();
 
     /**
@@ -93,6 +101,15 @@
     bool hasPendingCommands() const;
 
     /**
+     *  Flushes pending draw commands, if any, and returns an image of the
+     *  current state of the surface pixels up to this point. Subsequent
+     *  changes to the surface (by drawing into its canvas) will not be
+     *  reflected in this image.  Will return NULL if the deferred canvas
+     *  was not constructed from an SkSurface.
+     */
+    SkImage* newImageShapshot();
+
+    /**
      *  Specify the maximum number of bytes to be allocated for the purpose
      *  of recording draw commands to this canvas.  The default limit, is
      *  64MB.