Alter SkCanvas::drawPicture (devirtualize, take const SkPicture, take pointer)

R=reed@google.com, bsalomon@google.com, mtklein@google.com

Author: robertphillips@google.com

Review URL: https://codereview.chromium.org/313613004
diff --git a/src/utils/SkDeferredCanvas.cpp b/src/utils/SkDeferredCanvas.cpp
index 02c2c5a..e244505 100644
--- a/src/utils/SkDeferredCanvas.cpp
+++ b/src/utils/SkDeferredCanvas.cpp
@@ -936,7 +936,7 @@
     this->recordedDrawCommand();
 }
 
-void SkDeferredCanvas::drawPicture(SkPicture& picture) {
+void SkDeferredCanvas::onDrawPicture(const SkPicture* picture) {
     this->drawingCanvas()->drawPicture(picture);
     this->recordedDrawCommand();
 }