Add mask layer and offsetFromLayoutObject info to GraphicsLayer JSON

R=ajuma
BUG=672077
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2555283002
Cr-Commit-Position: refs/heads/master@{#437549}

third_party/WebKit/LayoutTests/compositing/masks/mask-layer-size-expected.txt

@@ -12,7 +12,14 @@
       "bounds": [400, 200],
       "contentsOpaque": true,
       "drawsContent": true,
-      "backgroundColor": "#000000"
+      "backgroundColor": "#000000",
+      "maskLayer": [
+        {
+          "name": "Mask Layer",
+          "bounds": [400, 200],
+          "drawsContent": true
+        }
+      ]
     }
   ]
 }

third_party/WebKit/LayoutTests/fast/borders/overflow-hidden-border-radius-force-backing-store-expected.txt

@@ -14,7 +14,14 @@
     },
     {
       "name": "Child Containment Layer",
-      "bounds": [300, 300]
+      "bounds": [300, 300],
+      "maskLayer": [
+        {
+          "name": "Child Clipping Mask Layer",
+          "bounds": [300, 300],
+          "drawsContent": true
+        }
+      ]
     },
     {
       "name": "Ancestor Clipping Layer",

third_party/WebKit/Source/core/paint/FilterPainter.cpp

@@ -53,10 +53,11 @@ FilterPainter::FilterPainter(PaintLayer& layer,
 
   DCHECK(m_layoutObject);
 
-  if (clipRect.rect() != paintingInfo.paintDirtyRect || clipRect.hasRadius())
+  if (clipRect.rect() != paintingInfo.paintDirtyRect || clipRect.hasRadius()) {
     m_clipRecorder = WTF::wrapUnique(new LayerClipRecorder(
         context, *layer.layoutObject(), DisplayItem::kClipLayerFilter, clipRect,
         &paintingInfo, LayoutPoint(), paintFlags));
+  }
 
   if (!context.getPaintController().displayItemConstructionIsDisabled()) {
     CompositorFilterOperations compositorFilterOperations =

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

@@ -648,6 +648,12 @@ std::unique_ptr<JSONObject> GraphicsLayer::layerAsJSONInternal(
   if (m_position != FloatPoint())
     json->setArray("position", pointAsJSONArray(m_position));
 
+  if (flags & LayerTreeIncludesDebugInfo &&
+      m_offsetFromLayoutObject != DoubleSize()) {
+    json->setArray("offsetFromLayoutObject",
+                   sizeAsJSONArray(m_offsetFromLayoutObject));
+  }
+
   if (m_hasTransformOrigin &&
       m_transformOrigin !=
           FloatPoint3D(m_size.width() * 0.5f, m_size.height() * 0.5f, 0))
@@ -768,6 +774,24 @@ std::unique_ptr<JSONObject> GraphicsLayer::layerAsJSONInternal(
     json->setArray("squashingDisallowedReasons",
                    std::move(squashingDisallowedReasonsJSON));
   }
+
+  if (m_maskLayer) {
+    std::unique_ptr<JSONArray> maskLayerJSON = JSONArray::create();
+    maskLayerJSON->pushObject(
+        m_maskLayer->layerAsJSONInternal(flags, renderingContextMap));
+    json->setArray("maskLayer", std::move(maskLayerJSON));
+  }
+
+  if (m_contentsClippingMaskLayer) {
+    std::unique_ptr<JSONArray> contentsClippingMaskLayerJSON =
+        JSONArray::create();
+    contentsClippingMaskLayerJSON->pushObject(
+        m_contentsClippingMaskLayer->layerAsJSONInternal(flags,
+                                                         renderingContextMap));
+    json->setArray("contentsClippingMaskLayer",
+                   std::move(contentsClippingMaskLayerJSON));
+  }
+
   return json;
 }