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 36cdfe6537f2b5c110527b888b857cebd0ddd057..407a001701ce414d1bccd955e15ea18160f07601 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -1130,7 +1130,8 @@ void LayoutBlockFlow::AdjustLinePositionForPagination(RootInlineBox& line_box,
   logical_offset += delta;
   line_box.SetPaginationStrut(LayoutUnit());
   line_box.SetIsFirstAfterPageBreak(false);
-  if (!View()->GetLayoutState()->IsPaginated())
+  LayoutState* layout_state = View()->GetLayoutState();
+  if (!layout_state->IsPaginated())
     return;
   LayoutUnit page_logical_height = PageLogicalHeightForOffset(logical_offset);
   if (!page_logical_height)
@@ -1168,6 +1169,8 @@ void LayoutBlockFlow::AdjustLinePositionForPagination(RootInlineBox& line_box,
     }
     if (ShouldSetStrutOnBlock(*this, line_box, logical_offset, line_index,
                               page_logical_height)) {
+      DCHECK(!IsTableCell());
+      pagination_strut += layout_state->HeightOffsetForTableHeaders();

[mstensho (USE GERRIT), 2017/05/29 10:22:00]

I was actually expecting this one to go away, now that
CalculatePaginationStrutToFitContent() always adds in this.

       // 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 +1197,11 @@ 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))
-      strut_to_propagate = logical_offset;
+                              page_logical_height)) {
+      DCHECK(!IsTableCell());
+      strut_to_propagate =
+          logical_offset + layout_state->HeightOffsetForTableHeaders();

[mstensho (USE GERRIT), 2017/05/29 10:22:00]

This one we need to keep, though, since CalculatePaginationStrutToFitContent()
isn't used.

+    }
   } 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