Don't add artifical 1 pixel width to empty tables

Source/core/layout/TableLayoutAlgorithmAuto.cpp

Index: Source/core/layout/TableLayoutAlgorithmAuto.cpp
diff --git a/Source/core/layout/TableLayoutAlgorithmAuto.cpp b/Source/core/layout/TableLayoutAlgorithmAuto.cpp
index b0a11f06aa0570e29c76d901469ac9a9c1098d14..fbd120cb1473575a27b7972fb543838f338cb16a 100644
--- a/Source/core/layout/TableLayoutAlgorithmAuto.cpp
+++ b/Source/core/layout/TableLayoutAlgorithmAuto.cpp
@@ -26,6 +26,7 @@
 #include "core/layout/LayoutTableCell.h"
 #include "core/layout/LayoutTableCol.h"
 #include "core/layout/LayoutTableSection.h"
+#include "core/layout/LayoutText.h"
 #include "core/layout/TextAutosizer.h"
 
 namespace blink {
@@ -63,15 +64,15 @@ void TableLayoutAlgorithmAuto::recalcColumn(unsigned effCol)
 
                 if (current.inColSpan || !cell)
                     continue;
+                columnLayout.columnHasNoCells = false;
 
-                bool cellHasContent = cell->children()->firstChild() || cell->style()->hasBorder() || cell->style()->hasPadding() || cell->style()->hasBackground();
+                bool cellHasContent = cell->minPreferredLogicalWidth();
                 if (cellHasContent)
                     columnLayout.emptyCellsOnly = false;
 
                 // A cell originates in this column. Ensure we have
                 // a min/max width of at least 1px for this column now.
                 columnLayout.minLogicalWidth = std::max<int>(columnLayout.minLogicalWidth, cellHasContent ? 1 : 0);
-                columnLayout.maxLogicalWidth = std::max<int>(columnLayout.maxLogicalWidth, 1);
 
                 if (cell->colSpan() == 1) {
                     columnLayout.minLogicalWidth = std::max<int>(cell->minPreferredLogicalWidth(), columnLayout.minLogicalWidth);
@@ -373,13 +374,13 @@ int TableLayoutAlgorithmAuto::calcEffectiveLogicalWidth()
                 int totalWidth = 0;
                 for (unsigned pos = effCol; pos < lastCol; ++pos) {
                     if (!m_layoutStruct[pos].effectiveLogicalWidth.hasPercent())
-                        totalWidth += m_layoutStruct[pos].effectiveMaxLogicalWidth;
+                        totalWidth += m_layoutStruct[pos].clampedEffectiveMaxLogicalWidth();
                 }
 
                 for (unsigned pos = effCol; pos < lastCol && totalWidth > 0; ++pos) {
                     if (!m_layoutStruct[pos].effectiveLogicalWidth.hasPercent()) {
                         float percent = percentMissing * static_cast<float>(m_layoutStruct[pos].effectiveMaxLogicalWidth) / totalWidth;
-                        totalWidth -= m_layoutStruct[pos].effectiveMaxLogicalWidth;
+                        totalWidth -= m_layoutStruct[pos].clampedEffectiveMaxLogicalWidth();
                         percentMissing -= percent;
                         if (percent > 0)
                             m_layoutStruct[pos].effectiveLogicalWidth.setValue(Percent, percent);
@@ -538,7 +539,7 @@ void TableLayoutAlgorithmAuto::layout()
             break;
         case Fixed:
             numFixed++;
-            totalFixed += m_layoutStruct[i].effectiveMaxLogicalWidth;
+            totalFixed += m_layoutStruct[i].clampedEffectiveMaxLogicalWidth();
             // fall through
             break;
         case Auto:
@@ -546,7 +547,7 @@ void TableLayoutAlgorithmAuto::layout()
                 numAutoEmptyCellsOnly++;
             } else {
                 numAuto++;
-                totalAuto += m_layoutStruct[i].effectiveMaxLogicalWidth;
+                totalAuto += m_layoutStruct[i].clampedEffectiveMaxLogicalWidth();
                 allocAuto += cellLogicalWidth;
             }
             break;
@@ -599,8 +600,12 @@ void TableLayoutAlgorithmAuto::layout()
         available += allocAuto;
         distributeWidthToColumns<float, Auto, NonEmptyCells, InitialWidth, StartToEnd>(available, totalAuto);
     }
+    if (available > 0 && numAutoEmptyCellsOnly) {

[mstensho (USE GERRIT), 2015/05/20 09:34:22]

A comment in front of this would be nice.

+        unsigned total = numAutoEmptyCellsOnly;
+        distributeWidthToColumns<float, Auto, EmptyCells, InitialWidth, StartToEnd>(available, total);
+    }
 
-    // Any remaining available width expands fixed width, percent width and non-empty auto width columns, in that order.
+    // Any remaining available width expands fixed width, percent width, non-empty auto width columns and empty auto width columns, in that order.

[mstensho (USE GERRIT), 2015/05/20 09:34:22]

Should you put the following inside a large else block? If there were empty
cells above, there should be no space left to distribute.

     if (available > 0 && numFixed)
         distributeWidthToColumns<float, Fixed, AllCells, ExtraWidth, StartToEnd>(available, totalFixed);
 
@@ -613,6 +618,11 @@ void TableLayoutAlgorithmAuto::layout()
         distributeWidthToColumns<unsigned, Auto, NonEmptyCells, LeftoverWidth, EndToStart>(available, total);
     }
 
+    if (available > 0) {
+        unsigned total = numAutoEmptyCellsOnly;
+        distributeWidthToColumns<unsigned, Auto, EmptyCells, LeftoverWidth, EndToStart>(available, total);
+    }
+
     // If we have overallocated, reduce every cell according to the difference between desired width and minwidth
     // this seems to produce to the pixel exact results with IE. Wonder is some of this also holds for width distributing.
     // This is basically the reverse of how we grew the cells.
@@ -641,6 +651,9 @@ void TableLayoutAlgorithmAuto::distributeWidthToColumns(int& available, Total to
         const Length& logicalWidth = m_layoutStruct[i].effectiveLogicalWidth;
         if (cellsToProcess == NonEmptyCells && logicalWidth.isAuto() && m_layoutStruct[i].emptyCellsOnly)
             continue;
+        // When allocating width to columns with nothing but empty cells we avoid columns that exist only to flesh out a colspan and have no actual cells.

[mstensho (USE GERRIT), 2015/05/20 09:34:22]

Could you break this comment into two lines?

+        if (cellsToProcess == EmptyCells && logicalWidth.isAuto() && (!m_layoutStruct[i].emptyCellsOnly || m_layoutStruct[i].columnHasNoCells))
+            continue;
         if (distributionMode != LeftoverWidth && logicalWidth.type() != lengthType)
             continue;
 
@@ -649,7 +662,7 @@ void TableLayoutAlgorithmAuto::distributeWidthToColumns(int& available, Total to
             if (lengthType == Percent)
                 factor = logicalWidth.percent();
             else if (lengthType == Auto || lengthType == Fixed)
-                factor = m_layoutStruct[i].effectiveMaxLogicalWidth;
+                factor = m_layoutStruct[i].clampedEffectiveMaxLogicalWidth();
         }
 
         int newWidth = available * factor / total;