Add a means of extracting active operations from SkPicture

src/core/SkPicture.cpp

Index: src/core/SkPicture.cpp
===================================================================
--- src/core/SkPicture.cpp	(revision 13766)
+++ src/core/SkPicture.cpp	(working copy)
@@ -248,6 +248,14 @@
     SkASSERT(NULL == fRecord);
 }
 
+const SkTDArray<void*>*  SkPicture::EXPERIMENTAL_getActiveOps(const SkIRect& queryRect) {
+    this->endRecording();
+    if (NULL != fPlayback) {
+        return fPlayback->getActiveOps(queryRect);
+    }
+    return NULL;
+}
+
 void SkPicture::draw(SkCanvas* surface, SkDrawPictureCallback* callback) {
     this->endRecording();
     if (fPlayback) {