Col width is not honored when dynamically updated and it would not make table narrower

Source/core/rendering/RenderTableCol.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 39 matching lines @@
     RenderBox::trace(visitor);
 }
 
 void RenderTableCol::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
     RenderBox::styleDidChange(diff, oldStyle);
 
     // If border was changed, notify table.
     if (parent()) {
         RenderTable* table = this->table();
-        if (table && !table->selfNeedsLayout() && !table->normalChildNeedsLayout() && oldStyle && oldStyle->border() != style()->border())
+        if (table && !table->selfNeedsLayout() && !table->normalChildNeedsLayout() && oldStyle && oldStyle->border() != style()->border()) {
             table->invalidateCollapsedBorders();
+        } else if (oldStyle && oldStyle->logicalWidth() != style()->logicalWidth()) {
+            // FIXME : setPreferredLogicalWidthsDirty is done for all cells as of now.
+            // Need to find a better way so that only the cells which are changed by
+            // the col width should have preferred logical widths recomputed.

[mstensho (USE GERRIT), 2015/01/09 21:21:35]

-"should".

+            table->recalcSectionsIfNeeded();

[mstensho (USE GERRIT), 2015/01/09 21:21:35]

See https://codereview.chromium.org/208263013/#msg11

How about walking the render tree (to find each cell) here, instead of using
things that rely on section ordering and grids being up-to-date? That way you
won't have to call recalcSectionsIfNeeded().

+            unsigned nEffCols = table->numEffCols();
+            for (RenderTableSection* section = table->topSection(); section; section = table->sectionBelow(section)) {
+                for (unsigned j = 0; j < nEffCols; j++) {
+                    for (unsigned i = 0; i < section->numRows(); i++) {
+                        RenderTableCell* cell = section->primaryCellAt(i, j);
+                        if (!cell)
+                            continue;
+                        cell->setPreferredLogicalWidthsDirty();
+                    }
+                }
+            }
+        }
     }
 }
 
 void RenderTableCol::updateFromElement()
 {
     unsigned oldSpan = m_span;
     Node* n = node();
     if (isHTMLTableColElement(n)) {
         HTMLTableColElement& tc = toHTMLTableColElement(*n);
         m_span = tc.span();
@@ skipping 108 matching lines @@
     return style()->borderStart();
 }
 
 const BorderValue& RenderTableCol::borderAdjoiningCellAfter(const RenderTableCell* cell) const
 {
     ASSERT_UNUSED(cell, table()->colElement(cell->col() - 1) == this);
     return style()->borderEnd();
 }
 
 }