[css-grid] Allow percentage values for column and row gutters

third_party/WebKit/Source/core/layout/LayoutGrid.h

Index: third_party/WebKit/Source/core/layout/LayoutGrid.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.h b/third_party/WebKit/Source/core/layout/LayoutGrid.h
index 2b7f531231f44fba6c4270a07ab86968c9e71a77..b0e73ab5f309962eefabd1a14f0fe37a87ed4f85 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.h
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.h
@@ -71,7 +71,7 @@ public:
         return m_rowPositions;
     }
 
-    LayoutUnit guttersSize(GridTrackSizingDirection, size_t span) const;
+    LayoutUnit guttersSize(GridTrackSizingDirection, size_t span, LayoutUnit availableSize) const;

[Manuel Rego, 2016/07/01 06:45:57]

I'm not really convinced about this API, specially it being public.

From the outside you shouldn't need to pass the avilableSize,
it should always use the availableLogicalWidth|Height() to determine
the gutter.

On top of that, we're already passing different values here
(contentLogicalWidth(),
availableLogicalWidth(), logicalWidth()). And this is just the initial patch,
we can pass more things in the future.

I really believe we should be able to do it internally, my approach would be
passing
the SizingOperation (actually in the public method don't pass anything
as it'd always be TrackSizing):
A) If we're computing intrinsic sizes the availableSize is always 0.
B) If we're in the track sizing phase, for columns the availableSize is
availableLogicalWidth()
   for rows, if the height of the grid container is indefinite it's 0,
  otherwise it's the availableLogicalHeight().

In most cases we'll be using the B) so that could be the default.

That way we avoid to pass this size over and over.

[svillar, 2016/07/13 09:08:08]

FWIW I'm making it private in the auto-fit patch.

 
     LayoutUnit offsetBetweenTracks(GridTrackSizingDirection direction) const
     {