Add snapshot entry point to SkPictureRecorder

include/core/SkPictureRecorder.h

Index: include/core/SkPictureRecorder.h
===================================================================
--- include/core/SkPictureRecorder.h	(revision 14346)
+++ include/core/SkPictureRecorder.h	(working copy)
@@ -82,6 +82,18 @@
         return NULL;
     }
 
+    /** Create an intermediate SkPicture of the in-progress recording.
+        Future recorded operations will not appear in the snapshot. If no
+        recording is in progress this will return NULL. 
+    */
+    SkPicture* snapshot() {
+        if (NULL != fPicture) {
+            return SkNEW_ARGS(SkPicture, (*fPicture));

[scroggo, 2014/04/25 14:16:52]

I haven't followed along with all the picture changes. Will this allow the
caller to continue recording after they've made the snapshot?

[robertphillips, 2014/04/25 14:55:28]

Currently - yes. I believe the desire is to not assume the burden of carrying
such a capability going forward.

[scroggo, 2014/04/25 15:00:44]

When that day comes, what will the Android approach be? Deprecate the Picture
copy constructor?

Could we have a function in picture recorder that copies the picture recorder?
Or is that a price we don't want to pay?

+        }
+
+        return NULL;
+    }
+
     /** Enable/disable all the picture recording optimizations (i.e.,
         those in SkPictureRecord). It is mainly intended for testing the
         existing optimizations (i.e., to actually have the pattern