Adjust paint invalidation rects to match the actual radius of rastered blur.

Skia actually renders to a larger radius than just blur().

BUG=648963,624175

Review-Url: https://codereview.chromium.org/2356213004
Cr-Commit-Position: refs/heads/master@{#420570}

third_party/WebKit/LayoutTests/TestExpectations

@@ -346,6 +346,33 @@ crbug.com/525889 imported/wpt/html/webappapis/scripting/processing-model-2/compi
 crbug.com/525889 imported/wpt/html/webappapis/scripting/processing-model-2/runtime-error-in-setInterval.html [ Failure ]
 crbug.com/525889 imported/wpt/html/webappapis/scripting/processing-model-2/runtime-error-in-setTimeout.html [ Failure ]
 
+crbug.com/648963 compositing/contents-opaque/overflow-hidden-child-layers.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/culling/scrolled-within-boxshadow.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/culling/translated-boxshadow.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/culling/unscrolled-within-boxshadow.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/geometry/foreground-layer.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/layer-creation/rotate3d-overlap.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/masks/masked-ancestor.html [ NeedsRebaseline ]
+crbug.com/648963 paint/invalidation/box-shadow-add-repaint.html [ NeedsRebaseline ]
+crbug.com/648963 paint/invalidation/box-shadow-change-repaint.html [ NeedsRebaseline ]
+crbug.com/648963 paint/invalidation/transform-replaced-shadows.html [ NeedsRebaseline ]
+crbug.com/648963 svg/css/text-gradient-shadow.svg [ NeedsRebaseline ]
+crbug.com/648963 svg/css/text-shadow-multiple.xhtml [ NeedsRebaseline ]
+crbug.com/648963 svg/zoom/page/zoom-background-images.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/masks/multiple-masks.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/masks/simple-composited-mask.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/scrolling-iframe.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/connect-compositing-iframe3.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/overlapped-iframe.html [ NeedsRebaseline ]
+crbug.com/648963 fast/borders/border-radius-mask-video-shadow.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/enter-compositing-iframe.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/iframe-resize.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/composited-parent-iframe.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/invisible-nested-iframe-show.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/connect-compositing-iframe-delayed.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/connect-compositing-iframe2.html [ NeedsRebaseline ]
+crbug.com/648963 compositing/iframes/connect-compositing-iframe.html [ NeedsRebaseline ]
+
 crbug.com/636961 [ Linux Debug ] virtual/threaded/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html [ Pass Failure ]
 
 crbug.com/552532 [ Win10 ] fast/replaced/no-focus-ring-embed.html [ Pass Crash ]

third_party/WebKit/Source/core/style/ShadowData.h

@@ -28,6 +28,7 @@
 #include "core/css/StyleColor.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/geometry/FloatRectOutsets.h"
+#include "platform/graphics/skia/SkiaUtils.h"
 
 namespace blink {
 
@@ -63,7 +64,9 @@ public:
     // shadow.
     FloatRectOutsets rectOutsets() const
     {
-        float blurAndSpread = blur() + spread();
+        // 3 * skBlurRadiusToSigma(blur()) is how Skia implements the radius of a blur. See also
+        // https://crbug.com/624175.
+        float blurAndSpread = ceil(3 * skBlurRadiusToSigma(blur())) + spread();
         return FloatRectOutsets(
             blurAndSpread - y() /* top */,
             blurAndSpread + x() /* right */,