Pad inval rects to compensate for Skia's hairline stroke

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index e4f5b18fb2b1b60eda7d99c92ecdb7a84c2130cb..a5dd1ce1e0ac31893481e511c6fc8c90a607ec11 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -2734,6 +2734,19 @@ struct SetContentsNeedsDisplayInRectFunctor {
   const DisplayItemClient& client;
 };
 
+IntRect CompositedLayerMapping::adjustedInvalRect(const LayoutRect& r) const {
+  // Skia's hairline stroke may extend .5 units outside the computed path
+  // bounds.  Pad defensively.
+  static constexpr float kInvalRectPadding = .5f;
+
+  LayoutRect adjustedRect(r);
+  adjustedRect.inflate(LayoutUnit(kInvalRectPadding));
+  adjustedRect.intersect(m_compositedBounds);
+  adjustedRect.move(m_owningLayer.subpixelAccumulation());
+
+  return enclosingIntRect(adjustedRect);
+}
+
 void CompositedLayerMapping::setContentsNeedDisplayInRect(
     const LayoutRect& r,
     PaintInvalidationReason invalidationReason,
@@ -2743,10 +2756,8 @@ void CompositedLayerMapping::setContentsNeedDisplayInRect(
   // spv2 is ready.
   // ASSERT(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
-  SetContentsNeedsDisplayInRectFunctor functor = {
-      enclosingIntRect(LayoutRect(
-          r.location() + m_owningLayer.subpixelAccumulation(), r.size())),
-      invalidationReason, client};
+  SetContentsNeedsDisplayInRectFunctor functor = {adjustedInvalRect(r),
+                                                  invalidationReason, client};
   ApplyToGraphicsLayers(this, functor, ApplyToContentLayers);
 }
 
@@ -2759,10 +2770,8 @@ void CompositedLayerMapping::setNonScrollingContentsNeedDisplayInRect(
   // spv2 is ready.
   // ASSERT(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
-  SetContentsNeedsDisplayInRectFunctor functor = {
-      enclosingIntRect(LayoutRect(
-          r.location() + m_owningLayer.subpixelAccumulation(), r.size())),
-      invalidationReason, client};
+  SetContentsNeedsDisplayInRectFunctor functor = {adjustedInvalRect(r),
+                                                  invalidationReason, client};
   ApplyToGraphicsLayers(this, functor, ApplyToNonScrollingContentLayers);
 }
 
@@ -2775,10 +2784,8 @@ void CompositedLayerMapping::setScrollingContentsNeedDisplayInRect(
   // spv2 is ready.
   // ASSERT(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
-  SetContentsNeedsDisplayInRectFunctor functor = {
-      enclosingIntRect(LayoutRect(
-          r.location() + m_owningLayer.subpixelAccumulation(), r.size())),
-      invalidationReason, client};
+  SetContentsNeedsDisplayInRectFunctor functor = {adjustedInvalRect(r),
+                                                  invalidationReason, client};
   ApplyToGraphicsLayers(this, functor, ApplyToScrollingContentLayers);
 }