Render the tab close button as a vector-based icon.

chrome/browser/ui/views/layout_constants.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/layout_constants.h"
 
 #include "base/logging.h"
 #include "ui/base/resource/material_design/material_design_controller.h"
 
 int GetLayoutConstant(LayoutConstant constant) {
   const int kIconLabelViewTrailingPadding[] = {2, 8, 8};
   const int kLocationBarBubbleHorizontalPadding[] = {1, 5, 5};
   const int kLocationBarBubbleVerticalPadding[] = {1, 3, 3};
   const int kLocationBarHeight[] = {0, 28, 32};
   const int kLocationBarHorizontalPadding[] = {3, 6, 6};
   const int kLocationBarVerticalPadding[] = {2, 2, 2};
   const int kOmniboxDropdownBorderInterior[] = {6, 0, 0};
   const int kOmniboxFontPixelSize[] = {16, 14, 14};
-  const int kTabCloseButtonTrailingPaddingOverlap[] = {3, 3, 3};
+  const int kTabCloseButtonTrailingPaddingOverlap[] = {2, 2, 2};
   const int kTabFaviconTitleSpacing[] = {4, 4, 4};
   const int kTabMaximumTitleWidth[] = {175, 175, 175};
   const int kTabPinnedContentWidth[] = {25, 25, 25};
 #if defined(OS_MACOSX)
   const int kTabstripTabOverlap[] = {19, 19, 19};
 #else
   const int kTabstripTabOverlap[] = {26, 26, 26};
 #endif
   const int kTabstripToolbarOverlap[] = {3, 3, 3};
   const int kTabstripTopShadowHeight[] = {3, 3, 3};
@@ skipping 81 matching lines @@
                          kToolbarBottomPadding[mode],
                          kToolbarRightPadding[mode]);
     case TOOLBAR_BUTTON: {
       const int inset = kToolbarButtonPadding[mode];
       return gfx::Insets(inset, inset, inset, inset);
     }
   }
   NOTREACHED();
   return gfx::Insets();
 }