Update our treatment of repeating headers in tables

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index 3dce15690fa8b723fd96c2a394fbccb3674cefcd..9456bc1f02e3b3d9c3f4e8b7e4fdd2b8dc8889e4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -1168,6 +1168,10 @@ void LayoutBlockFlow::AdjustLinePositionForPagination(RootInlineBox& line_box,
     }
     if (ShouldSetStrutOnBlock(*this, line_box, logical_offset, line_index,
                               page_logical_height)) {
+      if (!IsTableCell()) {

[mstensho (USE GERRIT), 2017/05/22 19:17:34]

Table cells should never accept struts, so this check is unnecessary. I suggest
that you change it to a DCHECK.

[rhogan, 2017/06/01 18:45:25]

Done.

+        pagination_strut +=
+            View()->GetLayoutState()->HeightOffsetForTableHeaders();
+      }
       // Note that when setting the strut on a block, it may be propagated to
       // parent blocks later on, if a block's logical top is flush with that of
       // its parent. We don't want content-less portions (struts) at the
@@ -1194,8 +1198,13 @@ void LayoutBlockFlow::AdjustLinePositionForPagination(RootInlineBox& line_box,
     // up in the next column or page. Setting a strut on the block is also
     // important when it comes to satisfying orphan requirements.
     if (ShouldSetStrutOnBlock(*this, line_box, logical_offset, line_index,
-                              page_logical_height))
+                              page_logical_height)) {
       strut_to_propagate = logical_offset;
+      if (!IsTableCell()) {

[mstensho (USE GERRIT), 2017/05/22 19:17:34]

Ditto.

[rhogan, 2017/06/01 18:45:24]

Done.

+        strut_to_propagate +=
+            View()->GetLayoutState()->HeightOffsetForTableHeaders();

[mstensho (USE GERRIT), 2017/05/22 19:17:34]

I think this is now the third time we do View()->GetLayoutState() in this
method. How about declaring a const layout_state variable instead?

[rhogan, 2017/06/01 18:45:25]

Done.

+      }
+    }
   } else if (line_box == FirstRootBox() && AllowsPaginationStrut()) {
     // This is the first line in the block. The block may still start in the
     // previous column or page, and if that's the case, attempt to pull it over