Introduce Layout*::adjustVisualRectForRasterEffects and use it for SVG hairlines.

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

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGShape.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGShape.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGShape.cpp
index 97ca82c6c64343e01cc3a24ed2ee8df1d20ea80e..4c2aa337f765e18065ee0ab92ce2a11dc7046bf0 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGShape.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGShape.cpp
@@ -45,6 +45,17 @@
 
 namespace blink {
 
+void LayoutSVGShape::adjustVisualRectForRasterEffects(
+    LayoutRect& visualRect) const {
+  // Account for raster expansions due to SVG stroke hairline raster effects.
+  if (styleRef().svgStyle().hasVisibleStroke()) {

[Xianzhu, 2016/10/24 16:17:30]

We should add !visualRect.isEmpty() to avoid inflating an empty rect to
non-empty.

[chrishtr, 2016/10/31 20:52:01]

Verified done by wangxianzhu.

+    float pad = 0.5f;

[Xianzhu, 2016/10/24 16:17:30]

Nit: s/float/LayoutUnit/

[chrishtr, 2016/10/31 20:52:01]

Verified done by wangxianzhu.

+    if (styleRef().svgStyle().capStyle() != ButtCap)
+      pad += 0.5f;
+    visualRect.inflate(LayoutUnit(pad));
+  }
+}
+
 LayoutSVGShape::LayoutSVGShape(SVGGeometryElement* node)
     : LayoutSVGModelObject(node),
       // Default is false, the cached rects are empty from the beginning.