Added showing slow scroll rectangles in Layers panel.

Source/core/inspector/InspectorLayerTreeAgent.cpp

Index: Source/core/inspector/InspectorLayerTreeAgent.cpp
diff --git a/Source/core/inspector/InspectorLayerTreeAgent.cpp b/Source/core/inspector/InspectorLayerTreeAgent.cpp
index 55762f82a85252a9ec973787903f0917f7d238f0..21479be8813fff75040a159e6d08d7aeb6289208 100644
--- a/Source/core/inspector/InspectorLayerTreeAgent.cpp
+++ b/Source/core/inspector/InspectorLayerTreeAgent.cpp
@@ -73,6 +73,44 @@ inline String idForLayer(const GraphicsLayer* graphicsLayer)
     return String::number(graphicsLayer->platformLayer()->id());
 }
 
+static void buildRegionObjects(const blink::WebVector<blink::WebRect>& regions,

[pfeldman, 2014/02/28 07:43:43]

Builders return objects: we have buildObjectFor and buildArrayFor that return
object and array. This one is rather populateRects, but I'd simply do
buildScrollRect(rect, type) and populate single list below using two for loops.

(Region is a CSS term, you probably want a different name.)

[malch, 2014/02/28 12:19:57]

Done.

+    TypeBuilder::Array<TypeBuilder::LayerTree::ScrollRect>& scrollRects,
+    const TypeBuilder::LayerTree::ScrollRect::Type::Enum& type,
+    const TypeBuilder::LayerTree::LayerId& layerId)

[pfeldman, 2014/02/28 07:43:43]

Looks like this is unused.

[malch, 2014/02/28 12:19:57]

Done.

+{
+    for (size_t i = 0; i < regions.size(); ++i) {
+        RefPtr<TypeBuilder::DOM::Rect> rectObject = TypeBuilder::DOM::Rect::create()
+            .setX(regions[i].x)
+            .setY(regions[i].y)
+            .setHeight(regions[i].height)
+            .setWidth(regions[i].width);
+        RefPtr<TypeBuilder::LayerTree::ScrollRect> regionObject = TypeBuilder::LayerTree::ScrollRect::create()
+            .setRect(rectObject)
+            .setType(type);
+        scrollRects.addItem(regionObject);
+    }
+}
+
+static PassRefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::ScrollRect> > buildScrollRectsForLayer(GraphicsLayer* graphicsLayer)
+{
+    RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::ScrollRect> > scrollRects = TypeBuilder::Array<TypeBuilder::LayerTree::ScrollRect>::create();
+    blink::WebLayer* webLayer = graphicsLayer->platformLayer();
+    buildRegionObjects(webLayer->nonFastScrollableRegion(), *scrollRects, TypeBuilder::LayerTree::ScrollRect::Type::RepaintsOnScroll, idForLayer(graphicsLayer));
+    buildRegionObjects(webLayer->touchEventHandlerRegion(), *scrollRects, TypeBuilder::LayerTree::ScrollRect::Type::TouchEventHandler, idForLayer(graphicsLayer));
+    if (webLayer->haveWheelEventHandlers()) {
+        RefPtr<TypeBuilder::DOM::Rect> rectObject = TypeBuilder::DOM::Rect::create()

[pfeldman, 2014/02/28 07:43:43]

Then you would be able to reuse builder method here and would actually save on
the number of lines. There is nothing wrong in building WebRect from the layer
data for the sake of the call.

[malch, 2014/02/28 12:19:57]

Done.

+            .setX(webLayer->position().x)
+            .setY(webLayer->position().y)
+            .setHeight(webLayer->bounds().height)
+            .setWidth(webLayer->bounds().width);
+        RefPtr<TypeBuilder::LayerTree::ScrollRect> regionObject = TypeBuilder::LayerTree::ScrollRect::create()
+            .setRect(rectObject)
+            .setType(TypeBuilder::LayerTree::ScrollRect::Type::WheelEventHandler);
+        scrollRects->addItem(regionObject);
+    }
+    return scrollRects->length() ? scrollRects : nullptr;
+}
+
 static PassRefPtr<TypeBuilder::LayerTree::Layer> buildObjectForLayer(GraphicsLayer* graphicsLayer, int nodeId)
 {
     blink::WebLayer* webLayer = graphicsLayer->platformLayer();
@@ -107,6 +145,10 @@ static PassRefPtr<TypeBuilder::LayerTree::Layer> buildObjectForLayer(GraphicsLay
         layerObject->setAnchorY(anchor.y());
         layerObject->setAnchorZ(anchor.z());
     }
+    RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::ScrollRect> > scrollRects =
+        buildScrollRectsForLayer(graphicsLayer);
+    if (scrollRects)
+        layerObject->setScrollRects(buildScrollRectsForLayer(graphicsLayer));

[pfeldman, 2014/02/28 07:43:43]

Why building twice, use scrollRects instead?

Do you need a check at all? I thought we supported nullable arrays.

[malch, 2014/02/28 12:19:57]

Done.

     return layerObject;
 }
 
@@ -202,7 +244,8 @@ void InspectorLayerTreeAgent::buildLayerIdToNodeIdMap(RenderLayer* root, LayerId
     }
 }
 
-void InspectorLayerTreeAgent::gatherGraphicsLayers(GraphicsLayer* root, HashMap<int, int>& layerIdToNodeIdMap, RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> >& layers)
+void InspectorLayerTreeAgent::gatherGraphicsLayers(GraphicsLayer* root, HashMap<int, int>& layerIdToNodeIdMap,
+    RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> >& layers)

[pfeldman, 2014/02/28 07:43:43]

no need for new line here.

[malch, 2014/02/28 12:19:57]

Done.

 {
     int layerId = root->platformLayer()->id();
     if (m_pageOverlayLayerIds.find(layerId) != WTF::kNotFound)