[SPv2] Introduce an option to output the GraphicsLayer tree as a flat layer list.

third_party/WebKit/Source/core/testing/Internals.idl

Index: third_party/WebKit/Source/core/testing/Internals.idl
diff --git a/third_party/WebKit/Source/core/testing/Internals.idl b/third_party/WebKit/Source/core/testing/Internals.idl
index 5a04edc91f18349df7b7cb731a8d9204365d0324..0f83ce648b3d051c523386b13b0c6f3f2ff0c903 100644
--- a/third_party/WebKit/Source/core/testing/Internals.idl
+++ b/third_party/WebKit/Source/core/testing/Internals.idl
@@ -187,6 +187,8 @@
     const unsigned short LAYER_TREE_INCLUDES_ROOT_LAYER = 8;
     const unsigned short LAYER_TREE_INCLUDES_CLIP_AND_SCROLL_PARENTS = 16;
     const unsigned short LAYER_TREE_INCLUDES_COMPOSITING_REASONS = 32;
+    const unsigned short OUTPUT_CHILDREN_AS_LAYER_LIST = 64;

[Xianzhu, 2016/09/30 23:19:38]

Nit: Should we use the same prefix as the existing flags?

[chrishtr, 2016/09/30 23:20:53]

The other ones all say LAYER_TREE, which seemed confusing to combine with
LAYER_LIST in the same breath.

[Xianzhu, 2016/10/01 00:14:03]

Acknowledged.

+
     [RaisesException] DOMString layerTreeAsText(Document document, optional unsigned short flags);
     [RaisesException] DOMString elementLayerTreeAsText(Element element, optional unsigned short flags);