LayoutSVGImage should work correctly even when image size is unavailable

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

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp b/third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp
index 1bce9cf781b9e3d55e4e815f6aa1d17cd2c83b77..d95b5566c8eaa959f28d00f8833bd4fa3cefbc9f 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGImage.cpp
@@ -69,7 +69,8 @@ static float resolveHeightForRatio(float width,
 
 FloatSize LayoutSVGImage::calculateObjectSize() const {
   ImageResourceContent* cachedImage = m_imageResource->cachedImage();
-  if (!cachedImage || cachedImage->errorOccurred())
+  if (!cachedImage || cachedImage->errorOccurred() ||
+      !cachedImage->isSizeAvailable())

[fs, 2016/12/20 10:08:12]

Would this not affect other similar code-paths simply because they either check
for the "empty" condition, or because the don't happen to use the (zero)
dimensions as denominators in a division? I'm not opposed to having this check
as such, but I wonder if makes sense to diverge w.r.t other similar uses.

[yhirano, 2016/12/20 12:06:30]

I'm not sure (I'm not familiar with the layout / image code). It looks dangerous
to me to read size when it is not available.

It is possible that we need more protection against 0-width and 0-height, but it
is a different issue, I think.

[fs, 2016/12/20 12:15:45]

My observation was mostly that other code seems to rely on that "no size
available" implies "size 0x0" (meaning one less property of the image to check.)
I'm fine with landing this change as-is though.

[hiroshige, 2016/12/21 17:51:06]

If we can replace isSizeAvailable() here and in ImageResource-related code with
0x0 size check, then it would be simpler (one less property that
ImageResourceContent should keep track), but it doesn't block this CL.

     return m_objectBoundingBox.size();
 
   FloatSize intrinsicSize = FloatSize(cachedImage->getImage()->size());