[CI] Cleanup SVG <pattern> attribute collection

Move the 'href' lookup to a helper function (as seen in the very similar
SVGGradientElement.) Use a similar setup in SVGGradientElement
equivalent method.
Move attribute synchronization from LayoutSVGResourcePattern into
SVGPatternElement::CollectPatternAttributes.
Change the SetPatternAttributes helper to take a SVGPatternElement
reference.
Remove the element null-check in the LayoutObject.

Bug: 769774
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I16901de05437bbeea1981f5340bec1a3e4329b50
Reviewed-on: https://chromium-review.googlesource.com/966221Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#543709}

third_party/WebKit/Source/core/layout/svg/LayoutSVGResourcePattern.cpp

@@ -136,18 +136,13 @@ SVGPaintServer LayoutSVGResourcePattern::PreparePaintServer(
     const FloatRect& object_bounding_box) {
   ClearInvalidationMask();
 
-  SVGPatternElement* pattern_element = ToSVGPatternElement(GetElement());
-  if (!pattern_element)
-    return SVGPaintServer::Invalid();
-
   // Validate pattern DOM state before building the actual
   // pattern. This should avoid tearing down the pattern we're
   // currently working on. Preferably the state validation should have
   // no side-effects though.
   if (should_collect_pattern_attributes_) {
-    pattern_element->SynchronizeAnimatedSVGAttribute(AnyQName());
-
     attributes_wrapper_->Set(PatternAttributes());
+    SVGPatternElement* pattern_element = ToSVGPatternElement(GetElement());
     pattern_element->CollectPatternAttributes(MutableAttributes());
     should_collect_pattern_attributes_ = false;
   }

third_party/WebKit/Source/core/svg/SVGGradientElement.cpp

@@ -188,11 +188,8 @@ void SVGGradientElement::CollectCommonAttributes(
 
 const SVGGradientElement* SVGGradientElement::ReferencedElement() const {
   // Respect xlink:href, take attributes from referenced element.
-  Element* referenced_element =
-      TargetElementFromIRIString(HrefString(), GetTreeScope());
-  if (!referenced_element || !IsSVGGradientElement(*referenced_element))
-    return nullptr;
-  return ToSVGGradientElement(referenced_element);
+  return ToSVGGradientElementOrNull(
+      TargetElementFromIRIString(HrefString(), GetTreeScope()));
 }
 
 Vector<Gradient::ColorStop> SVGGradientElement::BuildStops() const {

third_party/WebKit/Source/core/svg/SVGPatternElement.cpp

@@ -148,46 +148,56 @@ LayoutObject* SVGPatternElement::CreateLayoutObject(const ComputedStyle&) {
   return new LayoutSVGResourcePattern(this);
 }
 
-static void SetPatternAttributes(const SVGPatternElement* element,
+static void SetPatternAttributes(const SVGPatternElement& element,
                                  PatternAttributes& attributes) {
-  if (!attributes.HasX() && element->x()->IsSpecified())
-    attributes.SetX(element->x()->CurrentValue());
+  element.SynchronizeAnimatedSVGAttribute(AnyQName());
 
-  if (!attributes.HasY() && element->y()->IsSpecified())
-    attributes.SetY(element->y()->CurrentValue());
+  if (!attributes.HasX() && element.x()->IsSpecified())
+    attributes.SetX(element.x()->CurrentValue());
 
-  if (!attributes.HasWidth() && element->width()->IsSpecified())
-    attributes.SetWidth(element->width()->CurrentValue());
+  if (!attributes.HasY() && element.y()->IsSpecified())
+    attributes.SetY(element.y()->CurrentValue());
 
-  if (!attributes.HasHeight() && element->height()->IsSpecified())
-    attributes.SetHeight(element->height()->CurrentValue());
+  if (!attributes.HasWidth() && element.width()->IsSpecified())
+    attributes.SetWidth(element.width()->CurrentValue());
 
-  if (!attributes.HasViewBox() && element->HasValidViewBox())
-    attributes.SetViewBox(element->viewBox()->CurrentValue()->Value());
+  if (!attributes.HasHeight() && element.height()->IsSpecified())
+    attributes.SetHeight(element.height()->CurrentValue());
+
+  if (!attributes.HasViewBox() && element.HasValidViewBox())
+    attributes.SetViewBox(element.viewBox()->CurrentValue()->Value());
 
   if (!attributes.HasPreserveAspectRatio() &&
-      element->preserveAspectRatio()->IsSpecified())
+      element.preserveAspectRatio()->IsSpecified()) {
     attributes.SetPreserveAspectRatio(
-        element->preserveAspectRatio()->CurrentValue());
+        element.preserveAspectRatio()->CurrentValue());
+  }
 
-  if (!attributes.HasPatternUnits() && element->patternUnits()->IsSpecified())
+  if (!attributes.HasPatternUnits() && element.patternUnits()->IsSpecified()) {
     attributes.SetPatternUnits(
-        element->patternUnits()->CurrentValue()->EnumValue());
+        element.patternUnits()->CurrentValue()->EnumValue());
+  }
 
   if (!attributes.HasPatternContentUnits() &&
-      element->patternContentUnits()->IsSpecified())
+      element.patternContentUnits()->IsSpecified()) {
     attributes.SetPatternContentUnits(
-        element->patternContentUnits()->CurrentValue()->EnumValue());
+        element.patternContentUnits()->CurrentValue()->EnumValue());
+  }
 
   if (!attributes.HasPatternTransform() &&
-      element->HasTransform(SVGElement::kExcludeMotionTransform)) {
+      element.HasTransform(SVGElement::kExcludeMotionTransform)) {
     attributes.SetPatternTransform(
-        element->CalculateTransform(SVGElement::kExcludeMotionTransform));
+        element.CalculateTransform(SVGElement::kExcludeMotionTransform));
   }
 
   if (!attributes.HasPatternContentElement() &&
-      ElementTraversal::FirstWithin(*element))
-    attributes.SetPatternContentElement(element);
+      ElementTraversal::FirstWithin(element))
+    attributes.SetPatternContentElement(&element);
+}
+
+const SVGPatternElement* SVGPatternElement::ReferencedElement() const {
+  return ToSVGPatternElementOrNull(
+      TargetElementFromIRIString(HrefString(), GetTreeScope()));
 }
 
 void SVGPatternElement::CollectPatternAttributes(
@@ -196,19 +206,16 @@ void SVGPatternElement::CollectPatternAttributes(
   const SVGPatternElement* current = this;
 
   while (true) {
-    SetPatternAttributes(current, attributes);
+    SetPatternAttributes(*current, attributes);
     processed_patterns.insert(current);
 
-    // Respect xlink:href, take attributes from referenced element
-    Node* ref_node = SVGURIReference::TargetElementFromIRIString(
-        current->HrefString(), GetTreeScope());
+    // If (xlink:)href links to another SVGPatternElement, allow attributes
+    // from that element to override values this pattern didn't set.
+    current = current->ReferencedElement();
 
     // Only consider attached SVG pattern elements.
-    if (!IsSVGPatternElement(ref_node) || !ref_node->GetLayoutObject())
+    if (!current || !current->GetLayoutObject())
       break;
-
-    current = ToSVGPatternElement(ref_node);
-
     // Cycle detection
     if (processed_patterns.Contains(current))
       break;

third_party/WebKit/Source/core/svg/SVGPatternElement.h

@@ -89,6 +89,8 @@ class SVGPatternElement final : public SVGElement,
   void SvgAttributeChanged(const QualifiedName&) override;
   void ChildrenChanged(const ChildrenChange&) override;
 
+  const SVGPatternElement* ReferencedElement() const;
+
   LayoutObject* CreateLayoutObject(const ComputedStyle&) override;
 
   bool SelfHasRelativeLengths() const override;