Implement "dump displaylist" button for skia pipelines

Implement "dump displaylist" button in hierarchyviewer for skia
pipelines.

Test: ran hierarchyviewer for all pipelines.
bug: 34819877
Change-Id: Ifeb578260f636cb67268f9f9259e7318bf7de453
diff --git a/libs/hwui/RenderNode.h b/libs/hwui/RenderNode.h
index a971e83..c4ae82a 100644
--- a/libs/hwui/RenderNode.h
+++ b/libs/hwui/RenderNode.h
@@ -248,6 +248,8 @@
     // Called by CanvasContext when it drops a RenderNode from being a root node
     void clearRoot();
 
+    void output(std::ostream& output, uint32_t level);
+
 private:
     void computeOrderingImpl(RenderNodeOp* opState,
             std::vector<RenderNodeOp*>* compositedChildrenOfProjectionSurface,
@@ -266,7 +268,6 @@
 
     void incParentRefCount() { mParentCount++; }
     void decParentRefCount(TreeObserver& observer, TreeInfo* info = nullptr);
-    void output(std::ostream& output, uint32_t level);
 
     String8 mName;
     sp<VirtualLightRefBase> mUserContext;