cc: Make LayerTreeImpl dump layer list to FrameViewer and Devtools

third_party/WebKit/LayoutTests/http/tests/inspector/layers-test.js

 function initialize_LayerTreeTests()
 {
     InspectorTest.layerTreeModel = function()
     {
         if (!InspectorTest._layerTreeModel)
             InspectorTest._layerTreeModel = WebInspector.LayerTreeModel.fromTarget(InspectorTest.mainTarget);
         return InspectorTest._layerTreeModel;
     }
 
     InspectorTest.labelForLayer = function(layer)
@@ skipping 14 matching lines @@
         if (!prefix)
             prefix = "";
         if (!root) {
             root = InspectorTest.layerTreeModel().layerTree().contentRoot();
             if (!root) {
                 InspectorTest.addResult("No layer root, perhaps not in the composited mode! ");
                 InspectorTest.completeTest();
                 return;
             }
         }
-        InspectorTest.addResult(prefix + InspectorTest.labelForLayer(root));
+        if (root.drawsContent())

[vmpstr, 2016/05/31 22:16:16]

Why this change?

[sunxd, 2016/05/31 22:41:52]

See the comment in layer-tree.html, the background-color there forces the layer
to be draw.

+          InspectorTest.addResult(prefix + InspectorTest.labelForLayer(root));
         root.children().forEach(InspectorTest.dumpLayerTree.bind(InspectorTest, prefix + "    "));
     }
 
     InspectorTest.dumpLayers3DView = function(prefix, root)
     {
         if (!prefix)
             prefix = "";
         if (!root)
             root = WebInspector.panels.layers._layers3DView._rotatingContainerElement;
         if (root.__layer)
@@ skipping 72 matching lines @@
         };
         if (eventType === "mouseout") {
             eventArguments.screenX = 0;
             eventArguments.screenY = 0;
             eventArguments.clientX = 0;
             eventArguments.clientY = 0;
         }
         element.dispatchEvent(new MouseEvent(eventType, eventArguments));
     }
 }