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

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 583 matching lines @@
 
 static String pointerAsString(const void* ptr) {
   TextStream ts;
   ts << ptr;
   return ts.release();
 }
 
 std::unique_ptr<JSONObject> GraphicsLayer::layerTreeAsJSON(
     LayerTreeFlags flags) const {
   RenderingContextMap renderingContextMap;
+  if (flags & OutputChildrenAsLayerList) {
+    std::unique_ptr<JSONObject> json = JSONObject::create();
+    std::unique_ptr<JSONArray> layersArray = JSONArray::create();
+    for (auto& child : m_children)
+      child->layersAsJSONArray(flags, renderingContextMap, layersArray.get());
+    json->setArray("layers", std::move(layersArray));
+    return json;
+  }
   return layerTreeAsJSONInternal(flags, renderingContextMap);
 }
 
-std::unique_ptr<JSONObject> GraphicsLayer::layerTreeAsJSONInternal(
+std::unique_ptr<JSONObject> GraphicsLayer::layerAsJSONInternal(
     LayerTreeFlags flags,
     RenderingContextMap& renderingContextMap) const {
   std::unique_ptr<JSONObject> json = JSONObject::create();
 
   if (flags & LayerTreeIncludesDebugInfo)
     json->setString("this", pointerAsString(this));
 
   json->setString("name", debugName());
 
   if (m_position != FloatPoint())
@@ skipping 100 matching lines @@
     for (size_t i = 0; i < kNumberOfSquashingDisallowedReasons; ++i) {
       if (m_debugInfo.getSquashingDisallowedReasons() &
           kSquashingDisallowedReasonStringMap[i].reason)
         squashingDisallowedReasonsJSON->pushString(
             debug ? kSquashingDisallowedReasonStringMap[i].description
                   : kSquashingDisallowedReasonStringMap[i].shortName);
     }
     json->setArray("squashingDisallowedReasons",
                    std::move(squashingDisallowedReasonsJSON));
   }
+  return json;
+}
+
+std::unique_ptr<JSONObject> GraphicsLayer::layerTreeAsJSONInternal(
+    LayerTreeFlags flags,
+    RenderingContextMap& renderingContextMap) const {
+  std::unique_ptr<JSONObject> json =
+      layerAsJSONInternal(flags, renderingContextMap);
 
   if (m_children.size()) {
     std::unique_ptr<JSONArray> childrenJSON = JSONArray::create();
     for (size_t i = 0; i < m_children.size(); i++)
       childrenJSON->pushObject(
           m_children[i]->layerTreeAsJSONInternal(flags, renderingContextMap));
     json->setArray("children", std::move(childrenJSON));
   }
 
   return json;
 }
 
+void GraphicsLayer::layersAsJSONArray(LayerTreeFlags flags,
+                                      RenderingContextMap& renderingContextMap,
+                                      JSONArray* jsonArray) const {
+  jsonArray->pushObject(layerAsJSONInternal(flags, renderingContextMap));
+
+  if (m_children.size()) {
+    for (auto& child : m_children)
+      child->layersAsJSONArray(flags, renderingContextMap, jsonArray);
+  }
+}
+
 String GraphicsLayer::layerTreeAsText(LayerTreeFlags flags) const {
   return layerTreeAsJSON(flags)->toPrettyJSONString();
 }
 
 static const cc::Layer* ccLayerForWebLayer(const WebLayer* webLayer) {
   return webLayer ? webLayer->ccLayer() : nullptr;
 }
 
 String GraphicsLayer::debugName(cc::Layer* layer) const {
   String name;
@@ skipping 487 matching lines @@
 void showGraphicsLayerTree(const blink::GraphicsLayer* layer) {
   if (!layer) {
     fprintf(stderr, "Cannot showGraphicsLayerTree for (nil).\n");
     return;
   }
 
   String output = layer->layerTreeAsText(blink::LayerTreeIncludesDebugInfo);
   fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif