Serializing display lists

This is a WIP prototype

Change-Id: Id4bfcf2b7bf905221c3734b7b6887c9b2efd37e6
diff --git a/libs/hwui/renderthread/CanvasContext.h b/libs/hwui/renderthread/CanvasContext.h
index 0ceb9f1..6a79320 100644
--- a/libs/hwui/renderthread/CanvasContext.h
+++ b/libs/hwui/renderthread/CanvasContext.h
@@ -111,6 +111,8 @@
     void setName(const std::string&& name) { mName = name; }
     const std::string& name() { return mName; }
 
+    void serializeDisplayListTree();
+
 private:
     friend class RegisterFrameCallbackTask;
     // TODO: Replace with something better for layer & other GL object